contract cancelled

I was have been have a difficult time with vodacom since the day I took out that contract, I was finally able to cancel my contract last month and paid the last amount that was due and this amount was confirmed by one of the vodacom consultants! today I received a bill of R131.22 what the hell is this for? because they sent me an email stating that my number is now prepaid after I cancelled the contract! I am so damn sick and tired of vodacom