It is not your issue. The insurance and the doctor's office both committed an error and bad faith. Inform the doctor's office you will refuse payment and report the medical office to the medical board and to the state attorney general. File a complaint against the insurance company with your state's department of insurance and with the insurance company itself. Explain this is not your issue. Inform the doctor's office it committed the error and cannot bill you for any additional funds due to their negligence.