Personal Loan Settlement

I called to request a settlement amount. The letter was sent to me on 25/06/2020 (quote was to be paid before 07/07/2020). I paid a settlement amount on 29/06/2020 and when I called in to ask for a paid up letter was told that there's an outstanding amount that prohibits the account closure. When I enquired, the consultant told me that the request was not sent from their side hence the charges. I cannot pay for something that is not my fault, I want my account closed as I paid the settlement amount on time.