bad Service at FNB

I paid of my debt at FNB last month, and they still have not allocated my payment to the account and it seems like im still in debt with FNB. they are so quick to give you a letter of what you owe, but when you pay it off , they do not assist you to allocate the payment, I paid from FNB to FNB into the account nr provide by FNB and they still tell me every day , 'we are struggling to allocate your payment, and put your account to a Zero" when I phone in , (I phone every second day) they tell me the same story, but no one does anything about it. I have sent 12 emails to FNB, still no response!!! never again will I bank with FNB. my husband is at FNB, he will also take his account away,.