MTN Listed me on ITC and can get ahold of them EVEN AFTER IVE PAID MONTHS AGO!!!! Tuckshop company

If I had less stars I would rate it there. I closed and settled my MTN account a long time ago and MTN came back saying i owe money which was a small amount of 2000, due to im very busy i just settled it through Nimble and other companies that sub contract for MTN. So my ITC is showing as arrears and my credit score badly damaged as I want to purchase a vehicle. Guess what I cant reach MTN anywhere as I need to send them the paid up letter which Ive done months and months ago and just sent one today again to customercare and MTN Legal. No RESPONSE what so ever and my credit is damaged and keeps getting damaged. I cant apply for any credit what so ever because of MTNs poor processes. I cant even reach a consultant to speak to her and send her the paid up letter to clear me from ITC. HORRIBLE HORRIBLE Experience. Can some one just solve this little issue fast for me