My12k bill for data is insane!

I accepted an upgrade offer this year and I am on a 24 MTH My MTNChoice 100mins contract with 500MB and 200 smses. All of which I expected to be paying about R350 - 500 for. In fact in the first few months my bill was in the R600 range which I found reasonable. However, to my shock and horror today I received a bill stating that my current balance is R12000. I called customer relations and was advised that I had run up this bill for data usage between 15 July - 20 August. I cannot believe this! I have requested an itemised bill prior to disputing this account. I also checked my bank statements and see that in June my debit order was 2,681.01 and at the end of July they took 3400 from my account. This pattern is similar to what happened to another customer who was overcharged by 32k - see [URL Removed] <br> I am stumped and do not know how to proceed. <br> <br>