Contract cancelation

I requested my vodacom contract to be cancelled in March 2023 after they wanted to give me an upgrade.I was told that it would be cancelled and they never did They are still billing me.I requested again in May where they promised they will cancel.Today I received a call just to state that it's still not cancelled.No notes of my conversation in May and I have proof I called them hence I'm still being billed.This is unacceptable and tired to request the same thing.Why can't they listen to what the client wants.I only received the sms today that they will cancel after I threatened them.I request my money back since March and they must go check who did not do their job. I'm so furious and even considering canceling my other contract with them.