MTN keeps charging me what I already paid

I paid R800 in May which I later found out was allocated in their old system instead of the new. Since then and now I have had my line suspended, reminders of outstanding payment. The call centre people always tell me: 'we will escalate it' and until today, no change. Here are the references for my complaints 21/10/2020 *** 2020/10/15 *** 04/08/2020 *** 15/07/2020 *** I have been with MTN for 3 if not 4 contracts in a row and I have been due for an upgrade since July but I have lost interest in MTN. I just want this matter solved so I can find a competent Network.