Bad Service Concerning subscription cancellation

I have cancelled the Get More service with Cell C in October 2016 and to this day I am still being billed for this service. I am even going to reject their debit orders until they sort it out because it seems like it is the only way they will sort out my problem. I advised them that i don't use that service and I don't see a reason why I should pay for a service I do not use. I hate the fact that they confirmed that it has been cancelled but they still bill me and no one knows why it has not been cancelled. I WILL CANCEL THEIR DEBIT ORDER UNTIL THEY PAY UP!!! It seems to be my only solution to get their attention!