Money going for a contract I don't have.. Theft

I upgraded my phone last year with Vodacom online and after being sold and sent the wrong phone I returned it the 2 days later as it was a phone not worth my current contract. Vodacom still charged me for the next few months for a phone I didn't have. It's been so damn frustrating trying to get a hold of someone in the first place to cancel the contract initially and now deal with. Vodacom will so quickly and sweetly sell you the contact just to get your money but can't deliver. I would never reccomend Vodacom to anyone after this experience