Poor customer service and incompetence

I took a 24 months contract with vodacom, two years ago for two Iphone 6s with two sim cards, the main sim card is loaded with R175 airtime monthly and the secondary sim card was supposed to be loaded with R65 per month. The secondary sim card was never worked meaning it even that airtime was never received. I tried to report the matter countless times but the matter was never resolved. Now that the contract has ended I tried to cancel it and they assured me that it has been canceled but I’m still being billed for the contract. If I phone the cancellation department they tell me that it’s a business line and when I contact the business line cancellation they tell me that they don’t have that contract in their system. I don’t know what to do now. I’m frustrated and angry because they are de*****ing me and have been for the past two years.