MTN refusing to end contract after it has lapsed!

My MTN contract ended on the 31st of July 2021. I subsequently sent an email to *** requesting that my number be converted to prepaid immediately, ***. I got no response, so l wrote another email, ***. I got no response, got in touch MTN Twitter Support who told me they had escalated my query, nothing happened; and days went past. Contacted Twitter Support again, and they requested for my references; l gave them. Nothing happened. Then someone called my partner and told her to tell me to write an email to ***, AGAIN!!! I did AGAIN and got ***. MTN if you debit my account this month, l am going to raise a transaction dispute with my bank and reverse the amount! I want nothing to do with MTN anymore!