Vodacom not cancelling my contract

I phoned in on the 26 Jan 2016 to cancel my contract as it was due to end in Feb 2016. I was told that my contract would move over to prepaid in Feb. I phoned in again to complain about missing airtime on my tablet and found out I was going to be billed the full contract amount. I did my part in Jan to cancel the contract why should I be billed again? When I phoned in on the 21/3/16 the cancellations department guy was rude to me as he said he did not see the previous cancellation captured but the customer call centre lady who I spoke to first confirmed every detail. This is total BS!!! Now I wonder if the contract is really cancelled?!!