diff --git a/composer.json b/composer.json
index bd318502..de66fd50 100644
--- a/composer.json
+++ b/composer.json
@@ -39,7 +39,8 @@
         "friends-of-behat/variadic-extension": "^1.1",
         "lakion/mink-debug-extension": "^1.2.3",
         "phpspec/phpspec": "^4.0",
-        "phpstan/phpstan-shim": "^0.9.2",
+        "phpstan/phpstan-shim": "^0.10",
+        "phpstan/phpstan-webmozart-assert": "^0.10.0",
         "phpunit/phpunit": "^6.5",
         "sylius-labs/coding-standard": "^2.0",
         "symfony/browser-kit": "^3.4|^4.1",
@@ -62,5 +63,8 @@
             "vendor/bin/phpstan.phar analyse -c phpstan.neon -l max src/",
             "vendor/bin/ecs check src/ spec/"
         ]
+    },
+    "config": {
+        "sort-packages": true
     }
 }
diff --git a/features/refunding_single_order_unit.feature b/features/refunding_single_order_unit.feature
index 9cd1f840..a87c5cb1 100644
--- a/features/refunding_single_order_unit.feature
+++ b/features/refunding_single_order_unit.feature
@@ -57,13 +57,15 @@ Feature: Refunding a single order unit
         Then I should not be able to see refunds button
 
     @ui
-    Scenario: Being able to choose refund payment method
+    Scenario: Being able to choose only offline payment methods
         Given the order "#00000022" is already paid
         And the store allows paying with "Another offline payment method"
+        And the store has a payment method "ElonPay" with a code "IN_THRUST_WE_TRUST" and Paypal Express Checkout gateway
         When I want to refund some units of order "#00000022"
         Then I should be able to choose refund payment method
         And there should be "Space money" payment method
         And there should be "Another offline payment method" payment method
+        And there should not be "ElonPay" payment method
 
     @application
     Scenario: Not being able to refund unit from an order that is unpaid
diff --git a/phpstan.neon b/phpstan.neon
index 98566716..5fb202c1 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -1,3 +1,6 @@
+includes:
+    - vendor/phpstan/phpstan-webmozart-assert/extension.neon
+
 parameters:
     excludes_analyse:
         # Makes PHPStan crash
diff --git a/spec/Provider/OfflineRefundPaymentMethodsProviderSpec.php b/spec/Provider/OfflineRefundPaymentMethodsProviderSpec.php
new file mode 100644
index 00000000..30ba4cfd
--- /dev/null
+++ b/spec/Provider/OfflineRefundPaymentMethodsProviderSpec.php
@@ -0,0 +1,53 @@
+<?php
+
+declare(strict_types=1);
+
+namespace spec\Sylius\RefundPlugin\Provider;
+
+use Payum\Core\Model\GatewayConfigInterface;
+use PhpSpec\ObjectBehavior;
+use Sylius\Component\Core\Model\ChannelInterface;
+use Sylius\Component\Core\Model\PaymentMethodInterface;
+use Sylius\Component\Core\Repository\PaymentMethodRepositoryInterface;
+use Sylius\RefundPlugin\Provider\RefundPaymentMethodsProviderInterface;
+
+final class OfflineRefundPaymentMethodsProviderSpec extends ObjectBehavior
+{
+    function let(PaymentMethodRepositoryInterface $paymentMethodRepository): void
+    {
+        $this->beConstructedWith($paymentMethodRepository);
+    }
+
+    function it_implements_refund_payment_methods_provider_interface(): void
+    {
+        $this->shouldImplement(RefundPaymentMethodsProviderInterface::class);
+    }
+
+    function it_provides_only_offline_payment_methods(
+        PaymentMethodRepositoryInterface $paymentMethodRepository,
+        ChannelInterface $channel,
+        PaymentMethodInterface $offlinePaymentMethod,
+        PaymentMethodInterface $payPalPaymentMethod,
+        PaymentMethodInterface $stripePaymentMethod,
+        GatewayConfigInterface $offlineGatewayConfig,
+        GatewayConfigInterface $payPalGatewayConfig,
+        GatewayConfigInterface $stripeGatewayConfig
+    ): void {
+        $paymentMethodRepository->findEnabledForChannel($channel)->willReturn([
+            $offlinePaymentMethod,
+            $payPalPaymentMethod,
+            $stripePaymentMethod,
+        ]);
+
+        $offlinePaymentMethod->getGatewayConfig()->willReturn($offlineGatewayConfig);
+        $offlineGatewayConfig->getFactoryName()->willReturn('offline');
+
+        $payPalPaymentMethod->getGatewayConfig()->willReturn($payPalGatewayConfig);
+        $payPalGatewayConfig->getFactoryName()->willReturn('paypal');
+
+        $stripePaymentMethod->getGatewayConfig()->willReturn($stripeGatewayConfig);
+        $stripeGatewayConfig->getFactoryName()->willReturn('stripe');
+
+        $this->findForChannel($channel)->shouldReturn([$offlinePaymentMethod]);
+    }
+}
diff --git a/src/Action/Admin/OrderRefundsListAction.php b/src/Action/Admin/OrderRefundsListAction.php
index 1742923c..89784061 100644
--- a/src/Action/Admin/OrderRefundsListAction.php
+++ b/src/Action/Admin/OrderRefundsListAction.php
@@ -6,8 +6,8 @@
 
 use Sylius\Component\Core\Model\OrderInterface;
 use Sylius\Component\Core\Repository\OrderRepositoryInterface;
-use Sylius\Component\Core\Repository\PaymentMethodRepositoryInterface;
 use Sylius\RefundPlugin\Checker\OrderRefundingAvailabilityCheckerInterface;
+use Sylius\RefundPlugin\Provider\RefundPaymentMethodsProviderInterface;
 use Symfony\Component\HttpFoundation\RedirectResponse;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
@@ -23,8 +23,8 @@ final class OrderRefundsListAction
     /** @var OrderRefundingAvailabilityCheckerInterface */
     private $orderRefundingAvailabilityChecker;
 
-    /** @var PaymentMethodRepositoryInterface */
-    private $paymentMethodRepository;
+    /** @var RefundPaymentMethodsProviderInterface */
+    private $refundPaymentMethodsProvider;
 
     /** @var Environment */
     private $twig;
@@ -38,14 +38,14 @@ final class OrderRefundsListAction
     public function __construct(
         OrderRepositoryInterface $orderRepository,
         OrderRefundingAvailabilityCheckerInterface $orderRefundingAvailabilityChecker,
-        PaymentMethodRepositoryInterface $paymentMethodRepository,
+        RefundPaymentMethodsProviderInterface $refundPaymentMethodsProvider,
         Environment $twig,
         Session $session,
         UrlGeneratorInterface $router
     ) {
         $this->orderRepository = $orderRepository;
         $this->orderRefundingAvailabilityChecker = $orderRefundingAvailabilityChecker;
-        $this->paymentMethodRepository = $paymentMethodRepository;
+        $this->refundPaymentMethodsProvider = $refundPaymentMethodsProvider;
         $this->twig = $twig;
         $this->session = $session;
         $this->router = $router;
@@ -60,12 +60,10 @@ public function __invoke(Request $request): Response
             return $this->redirectToReferer($order);
         }
 
-        $paymentMethods = $this->paymentMethodRepository->findEnabledForChannel($order->getChannel());
-
         return new Response(
             $this->twig->render('@SyliusRefundPlugin/orderRefunds.html.twig', [
                 'order' => $order,
-                'payment_methods' => $paymentMethods,
+                'payment_methods' => $this->refundPaymentMethodsProvider->findForChannel($order->getChannel()),
             ])
         );
     }
diff --git a/src/Action/Admin/RefundUnitsAction.php b/src/Action/Admin/RefundUnitsAction.php
index 5aa763dd..a8af4857 100644
--- a/src/Action/Admin/RefundUnitsAction.php
+++ b/src/Action/Admin/RefundUnitsAction.php
@@ -12,6 +12,7 @@
 use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\HttpFoundation\Session\Session;
 use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
+use Webmozart\Assert\Assert;
 
 final class RefundUnitsAction
 {
@@ -46,6 +47,7 @@ public function __invoke(Request $request): Response
 
             $this->session->getFlashBag()->add('success', 'sylius_refund.units_successfully_refunded');
         } catch (CommandDispatchException $exception) {
+            Assert::notNull($exception->getPrevious());
             $this->session->getFlashBag()->add('error', $exception->getPrevious()->getMessage());
         } catch (\InvalidArgumentException $exception) {
             $this->session->getFlashBag()->add('error', $exception->getMessage());
diff --git a/src/Entity/CreditMemoUnit.php b/src/Entity/CreditMemoUnit.php
index c1610876..1d297a33 100644
--- a/src/Entity/CreditMemoUnit.php
+++ b/src/Entity/CreditMemoUnit.php
@@ -40,11 +40,17 @@ public function getTaxesTotal(): int
 
     public function serialize(): string
     {
-        return json_encode([
+        $serialized = json_encode([
             'product_name' => $this->productName,
             'total' => $this->total,
             'taxes_total' => $this->taxesTotal,
         ]);
+
+        if ($serialized === false) {
+            throw new \Exception('Credit memo unit could have not been serialized');
+        }
+
+        return $serialized;
     }
 
     public static function unserialize(string $serialized): self
diff --git a/src/Provider/OfflineRefundPaymentMethodsProvider.php b/src/Provider/OfflineRefundPaymentMethodsProvider.php
new file mode 100644
index 00000000..1dcbc158
--- /dev/null
+++ b/src/Provider/OfflineRefundPaymentMethodsProvider.php
@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Sylius\RefundPlugin\Provider;
+
+use Sylius\Component\Core\Model\ChannelInterface;
+use Sylius\Component\Core\Model\PaymentMethodInterface;
+use Sylius\Component\Core\Repository\PaymentMethodRepositoryInterface;
+use Webmozart\Assert\Assert;
+
+final class OfflineRefundPaymentMethodsProvider implements RefundPaymentMethodsProviderInterface
+{
+    /** @var PaymentMethodRepositoryInterface */
+    private $paymentMethodRepository;
+
+    public function __construct(PaymentMethodRepositoryInterface $paymentMethodRepository)
+    {
+        $this->paymentMethodRepository = $paymentMethodRepository;
+    }
+
+    public function findForChannel(ChannelInterface $channel): array
+    {
+        return array_filter(
+            $this->paymentMethodRepository->findEnabledForChannel($channel),
+            function (PaymentMethodInterface $paymentMethod): bool {
+                Assert::notNull($paymentMethod->getGatewayConfig());
+
+                return $paymentMethod->getGatewayConfig()->getFactoryName() === 'offline';
+            }
+        );
+    }
+}
diff --git a/src/Provider/RefundPaymentMethodsProviderInterface.php b/src/Provider/RefundPaymentMethodsProviderInterface.php
new file mode 100644
index 00000000..f0f27411
--- /dev/null
+++ b/src/Provider/RefundPaymentMethodsProviderInterface.php
@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Sylius\RefundPlugin\Provider;
+
+use Sylius\Component\Core\Model\ChannelInterface;
+use Sylius\Component\Core\Model\PaymentMethodInterface;
+
+interface RefundPaymentMethodsProviderInterface
+{
+    /** @return array|PaymentMethodInterface[] */
+    public function findForChannel(ChannelInterface $channel): array;
+}
diff --git a/src/Resources/config/services/actions.xml b/src/Resources/config/services/actions.xml
index e886b464..bcbe9bd6 100644
--- a/src/Resources/config/services/actions.xml
+++ b/src/Resources/config/services/actions.xml
@@ -18,7 +18,7 @@
         <service id="Sylius\RefundPlugin\Action\Admin\OrderRefundsListAction">
             <argument type="service" id="sylius.repository.order" />
             <argument type="service" id="Sylius\RefundPlugin\Checker\OrderRefundingAvailabilityChecker" />
-            <argument type="service" id="sylius.repository.payment_method" />
+            <argument type="service" id="Sylius\RefundPlugin\Provider\RefundPaymentMethodsProviderInterface" />
             <argument type="service" id="twig" />
             <argument type="service" id="session" />
             <argument type="service" id="router" />
diff --git a/src/Resources/config/services/provider.xml b/src/Resources/config/services/provider.xml
index 9add5e64..7f835333 100644
--- a/src/Resources/config/services/provider.xml
+++ b/src/Resources/config/services/provider.xml
@@ -31,5 +31,9 @@
         <service id="Sylius\RefundPlugin\Provider\RelatedPaymentIdProviderInterface" class="Sylius\RefundPlugin\Provider\DefaultRelatedPaymentIdProvider">
             <argument type="service" id="sylius.repository.order" />
         </service>
+
+        <service id="Sylius\RefundPlugin\Provider\RefundPaymentMethodsProviderInterface" class="Sylius\RefundPlugin\Provider\OfflineRefundPaymentMethodsProvider">
+            <argument type="service" id="sylius.repository.payment_method" />
+        </service>
     </services>
 </container>
diff --git a/tests/Behat/Context/Ui/RefundingContext.php b/tests/Behat/Context/Ui/RefundingContext.php
index da64caab..07547ad4 100644
--- a/tests/Behat/Context/Ui/RefundingContext.php
+++ b/tests/Behat/Context/Ui/RefundingContext.php
@@ -303,6 +303,14 @@ public function thereShouldBePaymentMethod(string $payment): void
         Assert::true($this->orderRefundsPage->isPaymentMethodVisible($payment));
     }
 
+    /**
+     * @Then there should not be :payment payment method
+     */
+    public function thereShouldNotBePaymentMethod(string $payment): void
+    {
+        Assert::false($this->orderRefundsPage->isPaymentMethodVisible($payment));
+    }
+
     private function provideLongComment(): string
     {
         return 'Tu ne quaesieris scire nefas, quem mihi quem tibi finem di dederint, Leuconoe, nec Babylonios temptaris numeros. Ut melius quidquid erit pati. Seu plures hiemes sue tribuit Iuppiter ultimam. Qae nunc oppositis debilitat pumicibus mare Tyrrenum: sapias vina liques et spatio brevi. Spem longam resecens. Dum loquimur fugerit invida Aetas: CARPE DIEM, quam minimum credula postero.';