I'm so sorry this is happening to you - I am actually mad for you, too! In what other profession can they just not do a good job (the scan didn't work, and you/your insurance paid for it - in every other profession you would get some kind of a refund or something!) So now you have to wait 90 days for a do-over??? That just sucks. I am super sorry. I wonder if there is some kind of medical reason that they won't just re-do it immediately?
I was going to a general practitioner for 15 months after sudden hearing loss. I literally had 7 appointments for ear problems as asked each time to be referred to an ENT. The GP had me try steroids, nellipot, every allergy medicine on the market, exercises, and antibiotics until I got so fed up I asked my awesome pediatrician who she went to for a general practitioner and immediately made an appointment with that provider. 2 days after my appointment with that GP, I was in the ENT's office and the next day was in the MRI machine.
I know "logically" you may actually just be told to "watch and wait" anyways, but it's like the emotional toll of going crazy thinking about all the unknowns is completely ignored. I hope you don't have an AN, but I will tell you when I was diagnosed, (when I finally saw the audiologist/ENT I told them I was pretty sure there was a "presence" in my face - I could sense it), there is a certain amount of peace that comes with the diagnosis - like at least you can make a plan. Big, big hugs.