Canceled contract

I called vodacom end of April to cancel my contract. They agreed and said I must pay the balance which was 168 at the time. I did pay but my contract was not canceled.

Last mont i an effort and called again to do another cancellation. This time I got even got a reference number and the agent said he will cancel it for me. They even called me to offer me low contract deals, but I refused. Boom today I recieve the same package I canceled, how coz I canceled the contract? An I am very sure they will expect me to pay it.