Charged for data I didn't use

I am very upset with Cell C. I have contracts with Cell C and I took second contract midlle of this year and when I took it there was a special of 3G for 4 months and 4months expired end of October. They gave me 3G beggining of November by mistake and they took it away within 2 days before I could use it and all of a sudden I am being billed for the 3g and my line was also suspended because I used the internet thinking that I have 3G without knowing it was already taken away and I was billed on my monthly limit. My debit order now includes the 3G that I didn't even use. Who does that, the call centre agents are also so *********** as well as their systems.