MTN cancellation ****

In 2022 entered into a contract with MTN which was 2 cellphones for 1. A year later in 2023 I called MTN because I wanted to settle the amount for the 2 cellphones. I was advised that I can't settle the SIM cards before contract end dates, I was ok with that. I paid the full amounts for the devices and i was left paying for the SIM cards only. A year later in July 2024, I got a call from an MTN agent letting me know that one of the SIM cards had reached it's 2 year full term contract and they wanted to know if I wanted to extend it. I politely declined and enquired what my options were. I was told I could extend the contract or move to prepaid. I opted for prepaid since I really didn't need that SIM card. On month end August I noticed that the debit order for the 1 SIM card left, which was a 3 year term, didn't go through. I then paid the contract money at the branch, but later on in the month I couldn't make calls because MTN had terminated my service because they claimed they didn't receive the money. I called their call centre to set the record straight and 8 was told I owe them R1115, mind you I was R115 for the 2 SIM cards. I asked what the R1000 was for and I was sent from pillar to post and eventually told it's a cancellation fee. I explained what had happened with the call centre agent. This was sent the department supervisor because the invoice had discrepancies in that it appeared as though the contract was cancelled and reopened the following day. I was advised to log a ***** complaint because this was done by an employee who had been discharged from work due to *****ulent claims. I logged the complaint and was sent to other various departments because it was either a cancellation or sales query. Remember my device had been blocked so I either had to borrow someone's phone or buy airtime for my Vodacom SIM to call MTN. This went on for over a week and I was frustrated. What I learnt from my calls was that I had apparently cancelled a device. I asked how can I possibly cancel a contract for a device which I had paid for in full, a year ago. Till today I have not gotten any proper answers from and yet they keep on sending me statements and invoiced with this debt that gets higher every month. They handed me over to their legal teams and I don't know what to do anymore because this is now affecting my credit record. Anyone able to assist or advise please feel free to do so. Thanks in advance