Change your contract under false information.

I had a call from MTN offering me one of their deals you know. After telling the sales rep I don't want my contract upgrade to be influenced or my monthly contribution to go up, he said it will all be the same except I will be paying less for what I am currently having. Just to find out that the month after that I am being billed almost double for my contract and the best is I don't know for what. they keep telling me they will get back to me, but they don't. I have even asked for my recording so that I can hear what was said and it was said that within 7 days I will be notified. its long past the 7 days and almost time for the money to be deducted. I am not happy, and I will not be leaving this issue here....