Bullying by Nedbank

On the 29th October I requested for a settlement quote at nedbank for a personal loan .A quote was sent to me. I paid the required amount. On the following day the debit order went off and it was not the normal debit date. I called nedbank to say but I have settled the loan. On the 8th of November the debit order was paid back. I also received a settlement letter. Yesterday a lady from nedbank called saying my loan is in arrears since I last paid R77000 last year October. We argued till she said I am owing them 5200 which they refunded me. I have a settlement letter. Proof of payment and the settlement quote with me.