Paying for a phone I don't have

After being with cell c for the last 10 years, Early January 2015 I upgraded my cell phone contract, I was not happy with the contract and I returned the phone with sim card that was wrong size in the first place and was told to call in 7 days time to get the contract reversed, After 7 days I called back to get the contract reversed and was told they had not received the phone and that I should phone back a few days later, after another 7 days (14 days total) I called back and the operator said they had record of the phone but there was no report issued and that I should phone back another day, phoned again today only to be told that there is still no report (21 days after return), I have given cell c more than enough time to asses the phone and the contract now needs to be reversed or legal action will have to be taken as I can not indefinitely be told to wait for a report whilst still paying for the phone. over and above the above mentioned cell c has now deactivated my original sim that I was still using on my old phone so I am now unable to receive or make calls. please reverse the contract and convert my sim to pre paid so that I can move to another network.