What do you mean by "should have been cleared by insurance?"
You are under an HMO and you saw a surgeon without a referral from a PCP?
Your surgeon ordered a bunch of tests and didn't bother to obtain prior authorization for what he ordered before you had them performed? Something else?
I'm having some trouble parsing this situation and understanding what's going on here.
If the co-surgeon was in-network, they shouldn't be trying to balance bill you until the claims are settled and the insurance company agrees that you either owe deductible or coinsurance money per the EOB. If that's the case, I would probably call up the co-surgeon's billing company and put the bill in "suspend", explaining that the claims are still pending. I had to appeal a claim once, and they were willing to suspend while it was working its way through appeal. You could also call up Anthem and ask them what the hold-up is regarding the claim.
If your
main surgeon was in-network, any assistant surgeon should still be considered in-network per the No Surprises Act.
If the main surgeon was OON, you're fucked, and they can balance bill/come after you for whatever they were unable to collect from insurance. Will be 100% on you to either pay or attempt to negotiate the bill amount down with the provider.
The first recourse you have is calling up the doctor/their biller and trying to bitch at them for not looking properly at the insurance. A good doctor might write off the bill, an asshole doctor will say "Your insurance is a contract between you and the insurer" and tell you to pound sand. If they tell you to pound sand and they are in-network, you can get your insurance company to hold the doctor's feet to the fire (i.e. file a grievance, which usually gets a doctor's attention, because they don't want a black mark on their record).
Decent stepwise guide to disputes here.
To my knowledge, the date of service determines payment. So if the services were rendered in 2023, and you already hit your out of pocket max in 2023, theoretically you would be reimbursed for 100% of whatever the allowable expenses are under your health plan. Anything your health plan specifically excludes would not be paid.