Oh my gosh! @hopenr! How terrible and frustrating for you. I had to get pre-approval as well, and was out of network naturally as I am in California and Mayo is in Rochester. There was some clause in my BC/BS plan that because it was being done at at COE and was not performed routinely anywhere but a few hospitals, it was approved. I ended up paying about $8000 out of pocket though! Ouch!
Perhaps take a deep breath and reach out once again to the link that our Everything Mayo Mentor @roch gave you...it is definitely a brick wall, but maybe there is someway around or over or under that wall.
My surgery was delayed five months due to Covid. October is only four months from now...that is what I would do, but I am not telling you do that, just saying! It is your decision.
You really want the best of the best, not the best of the rest. This is your life and you want to be in the hands of the top few places on the planet that do this surgery.
So re-group. Vent. Re-focus. Don't let this setback stop you from trying again. And again if you must...I am sorry you had to go through such a frustrating deal, but your name is Hope, and that a good thing to have. Faith is a good thing to have too...