What you might consider doing is looking up in your insurance companies online access what their criteria are for the procedure you’re having done. This way you and your doctor can fight the battle with better knowledge in hand. I used to perform insurance defense audits against insurance carriers for a health system in Pennsylvania. I’m certain it’s available from your Part B carrier as I presume you’re Medicare aged. Is this the procedure you’re seeking pre-authorization for?
https://www.mayoclinichealthsystem.org/hometown-health/speaking-of-health/radiofrequency-ablation-pain-relief