A reader of cashless.pl told us about a problem she encountered when returning purchases in one of the Mohito chain shops. "Unfortunately, I used a different card to the one I used to pay for the clothes. I gave the shop assistant my mBank card, originally using Millennium plastic. As a result, two months later I have no money on either my mBank or Millennium account," Ms Patrycja wrote to the editor.

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As a large proportion of cashless.pl readers probably know, as a general rule, refunds should be made to the card that was used for the original payment. Unfortunately, there are plenty of exceptions to this rule, where the procedure allows refunds to be made to another card.

Sometimes a customer has lost or misplaced a card due to theft and has had to block it. The new one issued by the bank already has an entirely different number, security code, expiry date, etc. In addition, more and more customers are not paying with plastic, but with their phone, where instead of a card there is only a token replacing the card number. When the phone is replaced, the token changes, so if a refund needs to be made, there is no way to credit it to the old token. Finally, there are cases where the refunds relate to purchases from several years ago, when the customer does not remember which card they paid with, and may even be long gone.

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What to do in the situation in which Ms Patrycja found herself? The funds probably went to the bank - the issuer of her card - and were credited to a technical account, as the institution could not identify the transaction associated with the refund. "The bank has 14 days to credit the refund. If the customer does not receive the money after this time, he or she should file a complaint with the bank whose card he or she used to make the refund", the mBank press office told me. In most cases, this should solve the problem. However, if this does not work - a similar complaint procedure should be started with the bank whose card was used to make the payment, and then ask for information about the refund from the shop that carried it out.