Cell C overbilling

I wish I could give Cell C a ZERO star rating. Their upgrade and new contract service is great....but they couldn't care less if you're an existing client. I have been overbilled for months and cannot get a straight breakdown from anyone at Cell C. I upgraded my contracts to reduce monthly charges....only to have Cell C INCREASE my billing amounts with LESS BENEFITS!!! The consultants get unmistakably annoyed and constantly talk over you. NO interest in your problem at ALLLLLL!! I was told Cell C can increase premiums on an EXISTING contract. How is this legal??? I would like Cell C to email me a detailed breakdown for the last 3 months....because their site is also not user friendly.