MTN service sucks big time!!!!!

I had a data contract which was to come to an end June 2022. I have given MTN notice on several occasions that I won't renew the contract. During the month of June I received notification that my contract was a promotion at R299 per month, which will come to an end and the monthly installment will increase to R1126. Again I called in notifying MTN that I'm not interested in renewing the contract and just want to go on prepaid as I've had my number for the past 20 years and don't want to lose it. My contract ran from the 17th to the 17th of each month when the data for the next month will be loaded. I get billed end of the month and End June I was billed the regular R299. In my mind I took the matter as settled. In July I got billed the R1126. I let it slide being lazy to follow up with MTN having come accustomed to their poor service of being sent you from one person to the next. August I again got billed the R1126. I then blocked the payment and called in to enquire why I'm still getting billed, since I was no longer receiving any data from MTN and was supposed to be on prepaid. I was told to rather make payment as I'll get blacklisted. I then laid a complaint with MTN and only received the automated message I'll be assisted within 48 hours. I never received any phonecall from MTN regarding my complaint. I made the payment fearing to get blacklisted. I went into the store in September and on the system it shows my account is in a credit and MTN owes me the R1126 and that my SIM is indeed on prepaid, no longer on contract. Surprise surprise end of September I got billed again. It's like someone has forgotten to stop my account and remove the debit order. I don't know what else to do to get this sorted. I'll definitely port my number once this mess is sorted as I want to get as far away from MTN as possible. The service sucks big time and I don't see it getting any better, so best I remove myself from such a stressful situation.