Cancelled Contract not Cancelled 2yrs later

When i upgraded my previos contract, i received the free R59 contract with the deal, which has not been used. When the contract came to an end, i called in last year to cancel it, as i have no use for it. A few months later, August 2019, I realised that the contract has still not been cancelled and called in again to cancel it. This time, being reassured that the process has been completed correctly. Upon checking my statements again this month, I can still see the contract being active and the amount being deducted from my account. This is nearly 1 and a half years after my initial request to cancel, and it has still not been cancelled. Vodacom does not care about its customers and are just taking their money, even after a cancellation request was completed. Are they even going to pay out for all those months of deductions, for a contract that has never ever been used? How do i ensure that this contract is cancelled.