19 days, No authorisation - membership revoked

I found Momentum Health online, decided that the products they advertise would suite my family better, and moved over from another medical aid. We joined the scheme on the 1st of June. Unfortunately my nearly 2yo son had an ear infection, referred to specialist by GP and surgery was required. Since the surgery was scheduled for the next day, I app**** for pre-authorisation immediately. Authorisation not given when surgery was to start, and I paid cash for theatre, thinking that Momentum will have authorisation sorted out soon. By 14 days after request, they informed me that they could not provide authorisation, my son will be removed from the medical aid, because he had ventilation tubes inserted 9 months ago for recurring ear infections, and no medical illness was disclosed to them when I joined their scheme. After a specialist inserted the tubes 9 months ago, my son's ear infections was a thing of the past, and was deemed healthy. No decision was provided to me in writing, no one seems able to address the situation. I'm more than disappointed with their service, since I've contacted them on numerous occasions to sort out the issue. They simply do not get back to you. Disgusting.