Unitas refusing to assist

My husband injured his knee a few weeks ago and needs to have knee surgery which is scheduled for Wednesday the 17th of Nov. He is currently in a lot of pain. We have medical aid and gap cover in place all in good order. The medical aid gave pre approval and the gap cover confirmed that we have a valid claim and the short fall (if any) will be covered. Now Unitas is insisting that we pay an estimate amount of R40 000 on the day of admission because there will likely be a shortfall. We've been going back and forth for two weeks now trying to explain that we do have gap cover that will cover the short fall and we will take responsibility for any costs that is not covered by our medical aid. Unitas is just refusing to assist in any way shape or form. What is the point of having medical aid and gap cover if you still have to magically make R40000 appear in case of an emergency?? This is why we have all of these things in place to ensure we get medical treatment when we need it! Absolutely pathetic on their part!