Migrating from contract to pre paid

After deciding to cancel my MTN contract I contacted the MTN call centre approximately a month before the contract expiry date, and enquired about the process to follow. I was instructed to phone the call centre with my cancellation request on the 28th of September 2015, which I did. I was then told that I had to settle my account (which I did) and that I will receive an SMS after a couple of days indicating that I am now a pre-paid customer. The call centre initiated the process, but when the SMS did not appear I phoned the call centre again and again to try and get it resolved. I eventually received an SMS, but not confirming my account cancellation, but rather a warning that I am in arrears with my payments. In a subsequent call centre call I was assured that my account was paid in full and that I will not be liable for any further costs since I followed the instructions to the T. (Ref ***). Sadly the cancellation request is still not complete. Numerous calls to the call centre and and escalation from the call centre to retentions only results in emails from retention that clearly indicates they do not look at the history and we start all over again. (Ref ***)