Virgin Mobile South Africa
Cancelled contract

I cancelled my contract in April 2013. I converted it to pre paid line. The consultant asured me that it is cancelled and that I still have to pay 2 payments. I did this. I took the sim out of my phone and never used it again. At the end of September 2013 I noticed that the debit order for this contract is still going of from my bank account. I phone virgin mobile and asked why this is happening. They said that they can see that I cancelled the contract but it still debiting. I asked them to rectify this and refund me the money that was deducted. They say they can not do this because the airtime was issued. I have not used that no since May. I know they can see this. I feel that they money from me and want it back. Please help