Nedbank service totally unacceptable - So disappointed

Nedbank service totally unacceptable - Am truly disappointed in the matter Nedbank is handling my case, I had a personal loan with them on the 25th of May 2020 i asked asked for a settlement letter and was told its valid for 5 working days, i made the full payment on the same day on Tuesday i called them back to check if payment is reflecting was told to wait, On Wednesday got the sms acknowledging payment.

I called requesting a confirmation letter that account was settled in full was told they have to request for it to be closed. 9 days later when i called am told i owe them R140 something rand because the loan is not closed and accumulated interest , so they delayed the process so i can pay more

Strange because i did ask the agents if the closing progress will add any interest on my loan they said no and i have recordings to prove that

How on earth can i still pay the bank more after i paid more than R11 000

Your services is the worst ever