MTN billing for services that were never requested

I renewed my contract at R99. This was a basic contract with absolutely no frills required. 6 months down the line i found out that I was being billed for additional data which I did not sign up for. I asked for this to be cancelled and for a refund of the additional billing as the data was never used as this mobile number is not currently is use since the renewel of the contract. i was asked by my outlet to contact MTN SA and when this was done MTN SA asked me to send the original contract which was duly done. since then...nothing. I have spoken to two of the consultants and these consultants do not repond to my e mails...lousy service t say the least.