Anthem is hitting me with $14,200 from an out of network surgical first assistant on my knee surgery - i thought the No Surprises Act covered this

need a reality check before i write this check or escalate. background: had ACL reconstruction in march at an in network hospital with my in network orthopedic surgeon. i confirmed both in writing with Anthem before scheduling because i had been burned on a prior MRI billing issue and was being paranoid. surgery itself went fine, recovery is on track.

then in june a bill shows up from "Surgical Solutions LLC" for $14,200 for a "surgical first assistant" who apparently was in the OR. i had never heard the company name. i did not sign anything for them. i was under general anesthesia when this person entered the room. they are out of network with Anthem.

called Anthem. they said because the assistant was out of network, they paid the assistant at the OON allowed amount ($1,800), the assistant company is balance billing me the rest, and Anthem considers it my responsibility. i pushed back citing the No Surprises Act - in network facility, ancillary provider i had no opportunity to choose, no consent form for OON care signed. the Anthem rep said the NSA "does not apply to surgical first assistants in this scenario" and would not explain why or cite the carveout.

has anyone fought through this exact situation? my read of the federal NSA is that ancillary providers at an in network facility (anesthesiologist, pathologist, radiologist, assistant surgeon) are explicitly covered unless i was given proper written notice and consented in advance, which i was not. is "surgical first assistant" somehow different from "assistant surgeon"? im in california so we have state balance billing law on top of the federal NSA - does that strengthen my position? do i file with CMS, state DOI, or both? do i pay the assistant company under protest and chase reimbursement from Anthem, or refuse to pay and let it sit? the assistant company is already sending past due notices.