update

modules/paynow/controllers/front/chargeBlik.php

@@ -81,7 +81,7 @@ class PaynowChargeBlikModuleFrontController extends PaynowFrontController
                             'external_id'   => $payment_data['external_id'],
                             'paymentId'     => $payment_data['payment_id'],
                             'paymentStatus' => $payment_data['status'],
-                            'token'         => Tools::encrypt($this->context->customer->secure_key)
+                            'token'         => PaynowCompatibilityHelper::encrypt($this->context->customer->secure_key)
                         ])
                     ]);
 

modules/paynow/controllers/front/payment.php

@@ -155,7 +155,7 @@ class PaynowPaymentModuleFrontController extends PaynowFrontController
         ])) {
             return PaynowLinkHelper::getReturnUrl(
                 $payment_data['external_id'],
-                Tools::encrypt($payment_data['external_id'])
+				PaynowCompatibilityHelper::encrypt($payment_data['external_id'])
             );
         }
 

modules/paynow/controllers/front/return.php

@@ -66,12 +66,14 @@ class PaynowReturnModuleFrontController extends PaynowFrontController
                 PaynowLogger::debug('Return: status processing failed', $statusToProcess);
             }
 
-            Tools::redirectLink(PaynowLinkHelper::getContinueUrl(
-                $this->order->id_cart,
-                $this->module->id,
-                $this->order->secure_key,
-                $this->payment->external_id
-            ));
+            PaynowCompatibilityHelper::redirect(
+				PaynowLinkHelper::getContinueUrl(
+					$this->order->id_cart,
+					$this->module->id,
+					$this->context->customer->secure_key,
+					$this->payment->external_id
+            	)
+			);
         }
 
         $currentState = $this->order->getCurrentStateFull($this->context->language->id);