Poor service, how do i cancel my contract?

Such poor service experience, constantly don't have signal, experience dropped calls not to mention for a full 8 hours i did not have a single bar of signal with no reason as to why this was the case. how do i actually cancel my vodacom account. I've tried to call the cancellation line just for a computer to answer. selected the option for a cancellation order but two weeks later still nothing, cant go into a branch to cancel the contract because they just tell you to call the call center. Utterly frustrated at this point, whats the point of having a phone you cant depend on because of continued poor service