Medical bill not being settled by Bonitas Medical Aid (Boncap)

My husband had to an allegergic reaction on 28 March 2021 and with no doctors open on a sunday he had to go to the emergency rooms at hospital. He previously visited and was admitted at Mercantile Hospital and had no issue with the medical aid covering the hospital and trauma unit bills. The medical aid authorisation department is not open on Sundays and we obtained a reference for authorisation on the Monday. After a whole range of emails we are now informed that the hospital bill is for our account as we did not obtain authorisation on the Sunday, the emergency room is considered as out of hospital and Mercantile Hospital is no longer the DSP but it was changed to Greenacres Hospital. No communication was sent regarding this change. My question is how do you get pre authorisation when the department is not open and if you have an emergency situation where you have an allergic reaction be expected to first find out if a bill will be covered by your medical aid if they are not operational?