Unable to request a cancellation when contract expires at MTN.

The first time I contacted MTN, they told me my contract ends 2017-10-30. I requested that they put in a request to cancel after that time and switch me to prepaid. They refused and said I should call back on the 18th October, this is when my airtime gets loaded. I tried calling on that day over the weekend without success. I was waiting on the phone for more than 2 hours. Then on the Monday I tried again, waited 15 minutes and got through. I ask them to put in a request to cancel and they were unable to do that. They told me I must call again on the 30th October. I find this kind of service mediocre and will not do business with MTN in the future. In fact I'm cancelling everything I have with MTN. I suggest MTN changes their process for cancellations.