Contract Cancellation

In October I called 084 143 to cancel my contract. The lady helped me very well. Received an SMS today that my January debit order will be R239. Phoned my nearest Cell C, the lady told me that nothing has been canceled. Called the number again to cancel my contract, now I must pay again. Why do I need to pay for some else's mistake? Now I can't get my money back because I used the benefits. Benefits that I didn't want in the first place.. Unacceptable!