cancellation of internet contract

i went to the telkom mobile store in alberton on the 19/06/2015 to cancel my internet promo 5 with tellkom, i was told by a consultant there that i will lose all my remaining data. so he adviced me to use all the remaining data and come back to cancel. i did exactly that. and went back on the 24/06/2015 to cancel. The same consultant told me that it was gonna be cancelled by the head office.now the shocking matter is that, when they debited my account for last month, they took R488-00 instead of R299 that i paid for the duration of the contract. telkom mobile even sent me an invoice showing that they are going to debit another R488-00 at the end of july. what part of \ I WANT TO CANCEL MY CONTRACT THESE GUYS DONT UNDERSTAND"This is my money they are taking out of my account. I am working hard for it. My contract ended in april with them. Can someone please tell these people to cancel this contract. I am not supposed to beg them to cancel it. It is an instruction. Telkom Mobile"