Furious over partial bill not covered by discovery

On Saturday 4th April (over the easter weekend) I took my wife to the GP because she wasn't feeling well for a few days. He found that she was pregnant, we opted for an ultrasound and he found there was no heartbeat which according to him is unusual based on the size of the foetus. He suggested that we go to the ER at the hospital. I called discovery and they suggested Cape Town Mediclinic which covers us instead of a hospital I opted for. My calls are all recorded. We went to the ER and they admitted my wife because there were no doctors over the easter period. Discovery was closed over the entire holiday period so I couldn't get through to them to find out if they have a doctor at this hospital who falls in the Discovery network rate but they were closed until Tuesday. Given the emergency we had to use doctors that the hospital appointed. Now I am slapped with a huge arrears amount all because discovery was unreachable over the easter period despite all my efforts to contact them which I don't feel is unacceptable. Why should I now be left with a partial bill that is not covered by discovery after I tried to contact them??