Vodacom taking money and not giving any service in return

I have, among others, a data contract with Vodacom. The sim was lost about 3 years ago. At first, I tried to do a sim swap, but although I am paying for the contract and receiving an invoice every month, Vodacom couldn't trace the number or pick it up on their system. After trying for a few months with no success I tried to cancel the contract and still they tell me that the contract is not active so they cannot cancel it. They invoice me every month, deduct the money every month for the past 3 years and they keep on telling me the contract is not active and therefore they cannot cancel it. I have phoned so many times and at the end of each call, a representative promises to investigate and call me back and they never do. Vodacom has the worst service ever!!! I cannot block the debit order because then they block the number that I use every day as well. So for 2 years, they have been taking my money and not providing any service in return. I have been paying for something that I don't even have and nobody at Vodacom can fix it and they will not refund the money that they just keep taking.