refund my money

I took a contract for 2 years with Vodacom and prior ending I called for cancelation because that is the procedure and after that they debited me 2 months after the contract has been canceled ,now they are billing me of things I do not understand on my pre-paid numbers and have not refunded me my money. The last time i spoke to someone which was last year he said he will listen to all my calls and get back to me of which he never did up until today!!!!!!!!!!!!!!!!!