Cancellation of a Contract

I took a contract with Cell C, It ends on the 27th of December according to the SMS I received . I contacted them on Monday the 21st to cancel the contract and requested confirmation from Zandile or Zanele that confirmation was not sent. I called them again on Thursday the 24th spoke to Tshepo who advised that the previous consultant is contacting me as we speak which did not happen, I had to call again 45 minutes later. I advised that all I am asking for is a letter confirming that my contract has been cancelled. He then sent me an Email with an incorrect date 31/07/2015 which was not even formal. Clearly he was not listening to me. This morning I contacted them again spoke to Sindi this was now frustrating requested to speak to a team leader after I explained to her what happened the previous week she then decided to transfer the call to Tshepo yet again who failed to send what I requested. Then he mentioned that he will transfer my call to the legal dpt which did not make sense. Finally spoke to a team leader Malapa who also seemed clueless. He advised that there is no cancellation of my contract on their system. REALLY CELL C??