Data package not cancelled and higher fees

My pre-paid data package has expired on 22/01/2015 (Sim no ***). The package was R118/m, but R299 was deducted end Feb. I phoned and cancel on 03 March (***) and was told that I should have cancelled at the end of the contract! - small print, not pointed out to me at purchase and no notification). I was told that I will only pay prorata for 4 days, but end of March R279 and end of April R318.68 was deducted. I want the cancellation to be made active and my money paid back which was taken from me by Cell C unauthorised. Now I have to call again on my own telephone cost to sort something out that was not done as agreed to.