Medical billing is a mess. Ask me how I found out a medical claim can be so incorrect insurance can deny it and not tell you about it.

It usually boils down to if the medical provider is in or out of network with your insurance.

In network provider = usually has a contract with insurance that says they can't bill you for anything insurance didn't approve. File a complaint with your insurance.

Out of network provider = you're SOL, they can charge what they want.