RCS loan paid in full but I still continue to receive SMEs that I still owe them money.

I paid the last installment on my RCS loan in February. After the payment was received by them they sent me an SMS stating that I still owe an amount on my loan. I phoned the call center and spoke to Thandi, who confirmed that my loan was indeed paid in full and that she would arrange for this to be updated and a letter confirming this would be sent to me. After all this, I received another SMS also stating that I still owe an amount on my loan. I feel that this unacceptable and I would appreciate it if this matter could be sorted out asap as I am really sick and tired of phoning the call center to try and sort this out.