Very unhappy client

My husband got hurt on the 28th of July, which was on a Sunday afternoon at 15h15. He had two deep lacerations to his head which needed urgent medical attention. I phoned Discovery ambulance who then took us to Garden City, which is the hospital we always use as it falls under our network. The doctor at casualty immediately treated him in casualty and sent him home afterwards. The following week when I went back to work, I received an SMS from Discovery stating that the they will only pay a portion of the Doctor's claim. When I phoned to enquire about this I was informed that the doctor we used wasn't our selected GP. Really?! in the 1st place, it was on a Sunday afternoon, our GP was already closed, 2ndly Garden City falls under our network, so how come the doctor doesn't fall under the designated service providers? Then I was informed to apply for a PMD, which I did, it was approved, but now Discovery is only paying 80% of the claim because the doctor is not a designated service provider. What I fail to understand is this: how is Garden City under our network but not the doctor? Does this mean that every time I have an emergency I will have to pay the doctor's bills? Who have time to worry about asking questions when faced with emergencies? I mean why must one pay for emergency treatment that was done in casualty? Where am I supposed to go to in an emergency when my selected GP is unavailable? What if I don't have time to first phone Discovery for authorization or worse still, what if I don't even have airtime to phone before going to the hospital?