Wrong bank account

I made a payment on the 18th of December to an Fnb credit card, only to find that it was supposed to be a standard bank credit card. But when I called capitec they told me the payment was successfully, the question is how because? Now my life is in danger 2 guys came and demanded the money because they've been waiting for far too long you can even check my calls I think I called for about 3 times.