Contract canncellation

I called Cell C on 27th July and spoke to Nomupumelelo Sibisi to cancel one of my contracts that had come to an end, ********** . She asked me why I didn`t want to upgrade and I told her my niece use to use this phone and she lost it way before the contract expired and she had gotten a new contract with other provider. Then 2 months down the line I noticed that I was still be billed for this phone. I called the Cell c Call centre only to be told that there was an upgrade done. The Call centre agent could see on the system that I had called on the 27th and gave me the name of the agent and was going to get her to call me. Her name was Nomupumelelo. She called me shortly and disputed my claim that I had asked her to cancel my contract. She said the only to resolve the matter was to retrieve the recordings of our call. She would have to call me back after having retrieved the recordings the next day. It`s been over 2 weeks now and she still has not called. The second debit order has since gone off after our conversation. I think this is totally unacceptable.