Unauthorized debits

I took out a contract for wifi router from CellC round about February. I immediately cancelled the contract at their N1 City mall branch and the guy who helped me spoke to one of the cellc consultants and said they cancelled it, as I realised they gave me the wrong product. He told me he could not keep the device as my contract was done telephonically and that the couriers must collect it from me. They told me they will come collect the product as none of their branches would take the product. I did not open nor use the product and yet CellC deducted from my personal account for a product/service I did not use and told them to cancel. After about 4-months of calling CellC numerous times and emailing them, they eventually collected the modem, still wrapped in the box. Cellc still deducted for months from my personal account. I contacted them again and again and went to my bank to block the deductions from my account.Somehow they debited from another account even more money from my personal account for a product that they had with them for months now already. The phone number the contract was on has been a prepaid number for someone else for months already and yet they still deduct from me. They owe me almost R3000 now but no one can tell me how they are still deducting from my account and when I will get my moneyor when the debits will stop. All of this will start affecting my credit record as I am now forced to go to the bank every time to stop the debits and its costing me hundreds of rands of airtime calling after them and yet they cant answer any of my questions and tell me when i will get my mony back. This is **************** and I am sick and tired of their bad service.