Need help navigating UMR through Nevada PEBP

In May of 2023 I thought I had a severe toothache and went to the dentist. After an xray he found a mass in my neck. It turns out I have a saliva gland stone. This shit hurts like hell everyday and seems to be in a constant state of infection. I can feel the pain in my ear, throat, teeth and neck. I was referred to an ear nose and throat specialist. He told be that I need a sialendoscopy (endoscopy of my saliva gland). He referred me to UC Davis but they said my insurance was not accepted there. I have contacted UMR 8 times now asking for a list of providers or facilities that perform the procedure I need. They refuse to give me anything helpful and basically just say it’s up to me to find what I need. My ENT doctor told me that no one in Nevada performs this procedure but my insurance should be contracted with a center of excellence that does(never heard this term but UC Davis is considered one of these). How can I get this information out of my insurance mafia? I’m just feeling helpless and angry with the whole situation. I just want a yes or no from them about whether they cover it or not.

See also  Kaiser SoCal insurance. Was told nearest Kaiser hospital was full and not to come and diverted to the closest hospital. How do I make sure this is covered?