Vodacom does not cancel on due date

I have a contract with Vodacom which was my late husbands phone. He passed away Nov 2016 and I had to keep this contract because it was on my name. Now I have requested a cancellation and the contract ends 3 October 2018 and was told by the agent that I have to pay for the rest of October and the contract will only end then? I feel that I have been paying for 2 years on something I did not use and now still another extra month