UHC and Banner: One Pre-Auth Approved Before Procedure, Other Denied 1 month After. Banner Billing Me for Full Cost of Unapproved

Hey all! Need some assistance here as I’m a bit lost as to what route to go with this situation.

I needed CT Arthrograms on both of my shoulders due to suspected labral tears in both. I can’t have MRIs due to metal in my body so we went the Arthrogram route.

I was referred to a Banner imaging center who said they’d need to re-send in for Pre-Auths and if they didn’t get approval in time we’d have to move back my procedure. That’s fine, I’m used to this song and dance with UHC where they deny and then we have to appeal for approval.

I got a letter for an approval, assumed we were good as I hadn’t heard anything from Banner to suggest otherwise. Both procedures were done mid-November, diagnosis on one shoulder confirmed and I had surgery recently to fix the tear.

I recently got a call saying my Pre-Auth was denied. I checked my UHC portal and they only approved the Arthrogram for one shoulder, with a denial decision for the second one coming a full month and a half after the initial request was made (not medically necessary 🙄).

Banner has now sent me a bill and wants their money for the procedure (around $800), but I’m super confused why they went ahead without full approval for both shoulders.

Who do I need to start with here? Banner or UHC?