In the event you need to make a refund, you will need to access your Wirecard account directly, also called the Wirecard Enterprise Portal. Here you can initiate refunds for processing and already settled transactions. Once you've initiated a refund, you will not be able to cancel.
It's important to note refunds are not the same as a chargeback. A chargeback is initiated by your customer and their bank on the grounds that your customer was subject to a fraudulent transaction. Once a transaction has been disputed this cannot be refunded.
However, sometimes a customer may have disputed a payment and simply forgotten the total and fail to recognise the payment on their bank statement. Other times, your customer may have been unhappy with the product or service you've sold them, for example if something broke during shipping. If your customer went straight to the bank instead of you to ask for a refund, you can get in touch with your customer, tell them you'll refund the money and save everyone the trouble, as long as your customer withdraws the dispute. If the dispute is withdrawn, you will be able to refund the payment like any other transaction.