Handed over because I am not paying my CANCELED CONTRACT

I signed a contract year ago for a data plan. It was not more than R200. Since then Cell c has been deducting from R400 to R600 a month just depends on I do not even know what. Okay, so I phoned in to get contract cancelled the consultant said I have to pay R320 in order for them to cancel my contract only after that she can cancel the contract. I made the payment received a sms stating that the contract will be terminated the end of the month. Great it's over now right? NO I still get phoned by lawyers cause apparently I've been handed over for non payment. When I ask for the reordered phone call that will prove I phoned in got the correct amount etc I get no response. They will just phone again telling me when I will be making payments on arrears. Then I have to start with the whole story again. They will just drop the phone in my ear to phone again and again. NICE WORK CELL C !!