No joy at MTN

The fastest way to damage your credit name is to open a MTN account. My contract ended Aug 2023. On 1 Jan 2024, they try to deduct R165 and when it did not gone through, they black listed me. For the past 5 years I had a clean record on clearscore, and now I'm trying to get my name cleared, but no success. I beg MTN for a letter showing that I don't owe them, but no answer. It is so frustrating. The ladies at the MTN shop says they cannot help me, I need to get it from Head Office.