FNB - MORE DIFFICULT TO SETTLE ACCOUNT THAN TO OPEN

I had accounts with FNB. 3 * loans, Credit Card & Overdraft. I settled all on the same day and with the settlement amounts on the settlement letter. However, they are taking their time to provide me with a paid-up letter and are even adding interest to one of the accounts. None of them were closes off, even though I called them and informed them, however they could not even give me reference numbers for my calls. I want a paid-up letter for each of the five accounts that I settled asap. It has now become more difficult to settle an account than to take out a loan.