Billing way above agreed premium

I have had an internet contract with Cell C for only two months. My contract is for a giga 20 including huawei modem for R199/month. after the first month my bank account was debited over R2500. after the second month four debit orders were taken off for R1291,R1291,R2405 and R2668. How can Cell C justify taking over R7000 when the contract is for R199 per month. I was told by a customer care representative that the reason is because some websites dont use data bundle data, they only use data out of bundle. what a load of B.S. I have only agreed to pay R199 per month. Even if that story is true then I only want the internet that I am entitled to for R199 per month. I have never authorised a greater debit order than R199 and I will never. Even if this problem is resolved I will never use Cell C again and I will use my dying breathes to make sure that no one else gets *****ed by Cell C either. I have contacted cell c a number of times with the promise that someone from the disputes department will contact me within 48 hours, 48 years maybe because i am still waiting and only getting more frustrated by the day.