Bad Service from Cell C

I have a data Account with Cell C. On Friday 27 April I logged in to check my balance on the account and noticed that my account was triple the amount it usually is, I pay a monthly fee of R198 per month for 3 gigs of data and the April account was for R740.00. I immediately phoned the call centre to query this amount and asked the consultant to explain why is this the amount this month, if i did not finish my data from the previous month and carried over unused data, how was I being charged for data. She promised to log a call and get back to me in two working days which happened to be Monday 30 April and Wednesday 2 May, imagine my surprise when on Thursday 3 May, I still did not receive a call from them, I called again on Wednesday, spoke to another consultant who promised exactly the same and logged another call and was promised a resolution by Thursday. Still to date, no response from Cell C. Everytime I call always get a consultant who promises to get someone to call and nothing happens.