Wrong info do not have Contract with Cell C

I received an account from cell C saying I am in arrears. I went to the SAPS to do sworn affidavit I am not in possession of that cell number. I have never signed any contract or document with them, I do not know what they are talking about. They must furnish me with the following documents: 1. I want to see the contract I signed 2. Copy of certified ID 3. The date and time when I signed contract 4. Copy of my payslip with certified copy of rates account. I receive a letter saying that they are giving me 7 days to pay R8524.10 which I am not aware of. I am now giving Cell C 3 days to come back to me with all the proof. I feel it is unfair to be charged for something you are not aware about. I tried to email customer service but the email came back delivery error when I try and call cell c to get information I get no where and when I go into internet they do not give me the email address that I can check. I need this to be investigated and for answers