Here’s a couple of discussions about appealing insurance decisions, the first one has info about the procedure which was useful for an insurance appeal:
I’m asking for my eagle syndrome familys help - General - Living with Eagle
Update …final appeal - General - Living with Eagle
I do agree with @Isaiah_40_31 that for VES, you do need a doctor with that experience if you can see one, & intra-oral surgery isn’t the best method for vascular issues… Good luck!