no feedback to billing query

In April I upgraded my cell phone and MTN once again forgot to do the migration and never credited me with my bundles. having fought for 5 months to have it sorted I was told last month it had been sorted. However my account has still not been sorted out properly and I am still being charged more than the agreed contract rate. I have queried this now two weeks ago and to date no one has bothered to get back to me. I am being threatened with suspension yet MTN takes 7 months to resolve an issue. I use WiFi just about all the time and hardly make calls so there is no reason why my usage should be outside the bundle size. If this issue is not resolved soon or if MTN should suspend my line then i will cancel my contract and move to a pay as you go method and I WILL keep the new iphone 6 MTN upgraded me to and MTN will NOT charge me for it as they have inconvenienced me more than enough to date since the upgrade. The level of service from MTN is totally shocking - one day alone I had to make almost 16 calls to the call center to resolve one issue that even the call center could not fix. Lets see if MTN will fix the problem now and personally contact me to apologize.