Contract cancellation

In 2014 I had a contract with Vodacom. At first I cancelled the contract before I could even use their device and asked them to come collect the phone because they had sent the wrong phone. That didn’t happen so I decided to continue with the contract. In 2016 when my contract ended I sent an email because I no longer needed to renew because I was not even using that number (Vodacom can pull records to show that number was not used) I was just waiting for the contract to end. Now today 2years later I get a call I’m told my account was handed over. How on earth is that possible when I had personally cancelled that contract? Now I’m told my cancellation was never received. Again how is that my problem when I had cancelled the damn contract. I’m sick and tired of service providers who wants us to cancel stuff via email and then we get told nothing was received. Is this a way of ripping people off by making extra money. Vodacom better have a solution because I am not paying for something I haven’t been using