Contract cancellation

I was told to pay the remainder of my amount needed to move me from a contract line to a prepaid line, send in a proof of payment and my id/passport for cancellation to be accepted. After a week this was still not done and cellC had gone on to bill me for my next month. On enquiry they told me I had to write a letter of cancellation, which had not been stated at 1st and I had not been followed up with after the first transaction. Now I have been billed for an additional month and I am still waiting for the cancellation to occur after submitting this letter!! Am I seriously forced to be on contract if I don't want to?! And they are telling me I will be debited end of February. My consultant Nokwanda from Rosebank mall was getting this information from Syethemba from TPHD a subsidiary of CellC