Vodacoms Failure to cancel expired contracts for years!!!!

I am trying to cancel a vodacom contract for years on end . The company fails to cancel this contract and continues to debit my account. I called countless times and they just fail to complete this simple task like. Im sure many are struggling with this dispicable customer service of vodacom. I wonder how much revenue is made annually from contracts that vodacom fails to cancel !! very disappointing and frustrating.