Cell C
Efuse to cancel my contract

I took out a contract at cell c for the I phone5. After receiving the phone i returned it the next day for numerous reasons. They took the phone in and almost months later the sales person comes to my worplace and says i must come get the phone or get someone else to take over the contract because they will not cancel it. Cell C is debiting my account with huge amounts and im forced to reverse their debits because i cannot afford it. I took out a contract at Game at a lesser price already. I need help please.