Account not resolved for five months

I had a top up account and wanted to downgrade back to pay as you go because I could no longer afford the top up option. I phoned MTN and was told they could not help me I need to go to a store. I went to MTN Cape Gate, Western Cape and they told me they can't help me, I must phone the call centre. I tried the call centre again and they referred me back to the store. On the 18th of August I emailed MTN requesting that they cancel my debit order and close my account as I have removed the sim card and am no longer using the service since July. I did not use any of the call or data time they sent me and they can check on their records to confirm. They gave me the run around because I couldn't remember passwords or security questions, keeping in mind I've had the same number since MTN became operational, it is still the old 083 number. How can I remember security questions. They keep sending me bills for this account, even though I have not used it since July 2023. Nobody will cancel it and correct the account. If I cant afford the top up account, how do you expect me to afford to pay from August to December for a service I don't use. I have moved to a better service provider with more affordable pay as you go options and excellent service from the call centre. Will anyone at MTN be able to do their job and sort this out?