Vodacom *****ing from Contracted Customers

I am with Vodacom since soon after it started, i.e. for more than 25 years. When my daughter was at primary school, I added her to my Vodacom contract. That went through her time at University and first years of employment. After she left South Africa in Jan 2019, I tried to cancel her service. 18 months later, still not cancelled, and they have thus ****** more than R8000 via a debit order. I have called them multiple times, email multiple times, commented on their FaceBook account, and even drove to VodaWorld, and I have still not been able to do this in almost 18 months. They do not even want to advise whether I should go to the Ombudsman, ICASA or Small Claims Court.