Contract Cancellation Nightmare

My contract with Vodacom was set to lapse in November and I called them twice to ensure that they terminate the contract when it ends. On the second call the cancellation consultant assured me that the cancellation request was sent and that the contract will be terminated when it lapses.

Imagine my surprise when I get an invoice for December???? I’m not going to pay it. I told Vodacom twice to cancel the contract and was assured that it was canceled.