Is it permissible to dispose of money that was returned to a credit card belonging to another person after it was used to pay for exam fees?

If the cardholder gifted the amount to the questioner, then the money belongs to the questioner, and if the bank refunds it, it remains his property. However, if the amount was a loan, the questioner must return it to the cardholder upon its recovery from the aforementioned entity. If the money was refunded by mistake, the questioner must return it to the entity that sent it. This is with a reminder of the impermissibility of dealing with credit cards issued by usurious banks.