Bad capitec attitude towards clients

I have made a loan in 2006 and when i went bck to school i stopped paying it up until i become employed in 2013 again then i have paid all my debts for capitec bank. I neveer asked for paid up letter but i was already handed over. I owe nothing for capitec bank since i have finished my debt. Surprisingly my owing status cannot be removed from their system and they only say,my account had been sold out. I have submitted my paid up letter but still the same story,and all they can say,is that my status with them will be like that forever..how does that happen