******** debit of bank account

cell c have been debit my account without any authorisation to do so, I am prepaid customer with cell c and NEVER taken a contract with cell c. I called customer service a month ago to have this matter resolved but unfortunately cell c has not been very helpful in regards to this matter, once again this month they have ********ly debit my account for the amount of R 2000. I called the customer service again and once again they were not helpful in resolving this matter, I have sent bank statements showing the several debit that have been done. They have told me that on their system I am seen as a prepaid customer but yet they have not rectified the problem. instead I had to call yesterday and make fuss for them to give me feedback and now they want copy of my ID and affidavit from the police station.... for what???? Why must I run around when they are in the wrong.... this *****!!!