Being overcharged every month

I renewed my Red Advantage contract with these people in Jan 2015 whereby they matched the offer Vodacom was offering as far as device was concerned and Data of 2 GB. I have been from the call centre to the top. And I get told every month that the other GB has been loaded, but every month I get charged for Data. I have even e-mailed the CEO Boyd Chislett on several occasions re the lack of service etc. to this day I have not received an e-mail nor a phone call from him. Mathapelo is the one that I have been dealing with and still can't get the problem fixed. The service is absolutely shocking from this company.