data overcharged

I have a contract on tel nr ***. It is a MTN Broadband 2GB. My understanding was that I pay for the 2GB data, and if I exceed, I will be notified. My children abused a data facility some two years ago, and I then specifically bought three contracts, all with the 2 GB facility at the same day, only to now learn that it is not capped! My take is that any reasonable person would expect that once the 2 GB has been utilized, you would be notified if there are now charges. The history of this usage on *** indicates that only once in the past did it exceed the 2 GB, but with a small amount, although I have not seen it, as we were not receiving the detail account. Despite being a client of Autopage since cell phones were introduced in SA, at my latest visit they claimed not to have my e-mail address! This has been rectified now. However, I insist that the charges beyond 2 GB be reversed! I have already cancelled this agreement to show my serious dissatisfaction with this. Instead of only being charged R109.65 per month, an additional charge of R7 150.64 has been debited. <br> I hereby declare that Autopage do NOT have the authority to debit my bank account with R7150.64