UNFAIR ITC LISTING

I'm so disappointed with MTNs horrible service. They have listed me on ITC when I settled the entire balance to the last 1 cent I was owing them. I have been waiting for a paid up letter since last year October up to date , when I call customer care they refer me to debt collectors stating that they no longer have my information, when I call debt collectors they say I'm owing R8000 for charges I don't know what charges. I've been sent from pillar to post to no luck and they have unfairly listed me on ITC , I curse the day j walked in at MTN really. Where else can I complain other than MTN and nudebt cz surely those people can not help me. DISAPPOINTED