Each state has its own procedure. In my state it is not complicated. I did this for the first time because of a repeated bad actor. evicore and aim off the hook here because these guys have their own internal team.
My state was very interested in the payer's conduct by the time I contacted them because of other complaints in other specialities. This payer is in process of being booted from our state. My understanding is that if certain corrective actions aren't taken, they will be booted. Worth remembering that each payer has to get auth at state level to do business in a given state so it's each state's dept of insurance (or whatever local name it goes by) that has the most direct jurisdiction over who can play and who can't in the state in question.
Other entities that are on my "speed dial" when I encounter what I determine to be arbitrary and/or not PUBLICLY-available-guideline-driven conduct are the National Committee for Quality Assurance NCQA and URAC Utilization Review Accreditation Commission. I also have my go to US Senator who, while not having direct jurisdiction of a state level matter, takes a great interest in helping my patients and this senator's office seem to get results. I prefer to bring pain from all directions as you can see.
If anyone from the insurance world is on here, my identify is now probably clear at least to them. I am a salaried employee with a directorship role and no production incentive of any kind (ie i get nothing to do imrt instead of 3d just as an example). What gets me up in the morning are my patients not getting ****** by crazy admin decisions, insurance stooges, or turncoat rad oncs who decide they need 10 k a month to bust the ***** of the rest of us. Get a life.