Vodacom is useless

Vodacom is excellent in opening accounts, but absolutely useless in closing an account. I am trying for almost a year now to cancel my contract. Eventually I stopped payments by instructing my bank to stop the debit order, and now I am being blacklisted by the credit bureau for being in arrears. I do not live in SA, so can only make whatsapp calls, which is not allowed by vodacom. And when I do manage to make a land line call and pay a lot of money for that, I am put on hold for very long and can only listen to non-sensical stupid options that do not address my issue. When you do speak to a real person, they promise everything is sorted, and it is for a month, and then they start again with debiting my account. If anyone can help with this, please do.