CellC bad service

I have a data contract that was to renew 18th June and payment would increase to R279 pm. A week later I get another call early June from CellC offering me another deal, where I would get an additional 20gb to the current 30gb anytime day I already receive at a reduced price of 202pm. Now I am still being debited R279 and no additional data. I want this rectified.