Complain - contract cancellation

I have been trying to cancel my contract with Vodacom, two attempts with no luck. The first guy who assisted me the first time offered me discount instead of canceling the contract. I agreed, to my surprise end of the month the full amount was debited. I again called, a lady assisted me and offered me a discount too and told me that they will invistigate, get a voice recording to check who assisted me. Just now I went to my Vodacom app to check my invoice, to my surprise nothing change I am still billed the same amount which I am no longer affording.