MTN Ping Pong - the only thing that they seem to be able to do properly...

MTN Ping Pong between Retentions and Billing - despite my best efforts and repeated explanations on the incorrect double billing of my account, still no resolution. Contract expires on 16th August. I contact MTN a week before to ask to move to prepaid and cancel contract. The offer me a reduced contract which I accept - this takes 1 week to resolve. They upgrade my contract one week after expiration and then double bill me at the old contract value. After 10 days of back and forth - still no resolution. I should have just cancelled and moved away. And off course every time I call, as you would, the call drops because of the MTN network. MTN has the unique ability to disappoint and frustrate its customers. Please can someone at MTN treat a customer of 20 odd years with a some degree of professionalism and courtesy?