Sometimes a refund attempt will result in an error message similar to this:

First, verify whether the card has been cancelled or the transaction linked to an inactive merchant. If it has been cancelled they may need to contact their bank to approve the refund.

If the card is active, you should let the customer know that you will call them back and then attempt the refund again in a few hours or the following day.

If the refund continues to fail, contact management.