Reference not working

On the 26th of May I went to your Braamfontein branch to get my reference number to use when paying my outstanding amount on my cancelled credit card. I have been unable to make payment on my banking app and always get an error ‘013-Enter a valid beneficiary account number.’ I have double checked this two weeks later with the same brand and they have confirmed the right reference to use at *** however this does not go through at all and I really need to make payment and settle this account.