Credit Card Complaint

I am very unhappy with how FNB has been treating me regarding my credit card issue. I had an aspire credit card and I upgraded to Premier Credit card in error, but I ended up going through with the Premier credit card, before I received the Premier Credit Card, I have been using the Aspire Credit Card, every transaction that I have made with Aspire is now reflecting on the Premier Credit Account and now the account is in arrears and I have been told that every amount that is under Aspire will transfer to Premier so I have one account but that hasn't been done. I am being harassed by the Credit Card Collections department requesting I pay an amount of R1753.27 of which I don't understand how I am owing when I made a payment of R1796. I am sick and tired of this and it's high time I shop around and move to another bank, mind you I have been with FNB over 12 years now but for the past few weeks FNB has been unloyal to me and this has affected my credit score of which I have worked hard for to build, so if this is not sorted by CLOSE OF BUSINESS TODAY, I AM DEFINETELY CANCELLING ALL MY CARDS AND MOVE OVER TO ANOTHER BANK.