Try to cancell my contract at cell c

We have a contract at cellc with 3 different numbers, one of the numbers can be updated now but we don't want to continue with the contract due to the fact that I never have signal with my mobile except when its connected to wivi. We contacted cellc to cancel the contract, they told us we must cancel early April so that it will be cancelled end of April and so we did. We contacted them via email as well on the 6 April. We called them on the 30 April and they said we must call tomorrowr then they will be able to see if it was cancelled. Today we went to cell c Middelburg Mall with really bad customer service just so they can tell us the contract is not cancelled they let me talk on the phone and the person on the phone gave us another number to phone, signal so bad the person couldn't hear me or maybe didn't want to hear. We called the call centre again and they said It can only be cancelled in end if March. Why do they keep telling us different story's every time? I want to cancel my contract ASAP. due to the bad service and paying for a network provider that doest work. Please help to get thus contract ended.