incorrect interest charged

Good day On the 25th November FNB really messed me up. I paid my credit card by doing a transfer but then that day in the evening they went to debit my account on the same date which was before the due date which is around the 28th without consulting me the same amount that i just paid that caused havoc in my account debit orders bounced off and then they charged all the unpaids amount for that. Then later on the day I was charged an interest of R 1023 interest on my cheque account this all happened on the 25th November 2017 and my usual interest rate on full usage of overdraft is around R580 . On the 7th December I called FNB to query this, I spoke to Zinhle in Premier banking to find why was charged this ridiculous interest. She couldn't answer me instead she told me about the interest charged everyday until is billed which i i know and understand then she tried to go the NCA interest rate which is currently is 20.75% and this is the maximum I can be charged which i know but i was charged more than the allowed NCA interest rate how nobody can answer me. Zinhle then went on to say i will ask our credit analyst to assist. I went to the branch they couldn't help me and this is the reference she claimed she logged ********** -M8M7N1 BUT 2 WEEKS later on the 19th dec 2017 when I was following up since no one had come back to me I find that she never logged the case she loaded interaction that we spoke nothing else. This time i spoke to Amina/Amisha forgot her name she couldn't answer or help but she promised that she will get the manager to contact same day which she did. Premier banking Manager Busi calls me but she she couldn't answer why was I charged this interest she promised also she will follow up the credit analyst to find what happened and she will come back till this day she has never called me back. So now I want FNB to reverse the extra interest rate that was charged on my account to be reversed and if not please provide an explanation why can't it be reversed and also state what was the interest rate charged and what is my personalised current interest rate so we can refer to the ombudsman . They are so quick to charge fees,penalties when a person makes a mistake but very slow to act when they have made a mistake