Cancelled contracts keeps debiting

I cancelled my 2 contracts when their term was up 3 months ago. It was not cancelled like i asked and they kept on debiting money for the cancelled contracts. I phoned numerous times and every time the consultant confirmed that the contract has been cancelled. Yet today it was debited again. I phoned and one of the contracts has been cancelled. They said i never cancelled the other. *****. I did every time. I want answers. Why would i cancel one and not the other. I have 2 more contracts with vodacom and will be cancelling them as soon as their time is up. I am finished with vodacoms incompetence.