Insurance denied my MRI - anyone successfully appealed this?

Got hit with a denial letter for an MRI my doctor ordered back in February. Reason given was "not medically necessary" - which is wild because I've had ongoing back pain for 8 months and my doctor literally wrote a referral explaining why.

I called the insurance line and they basically just read the denial letter back to me word for word. Completely useless. I asked to speak to a supervisor and the rep said someone would call back within 5 business days - that was 2 weeks ago, nothing.

Has anyone actually had success appealing a medical necessity denial? I'm supposed to get the MRI done regardless but $1,800 out of pocket is a lot. My plan is Blue Shield if that matters.