I am handling the estate of my late step-father. In November 2021 he was in the hospital and had lab work done. The lab company sent the claim to the wrong insurance. My mother & insurance company called the lab with correct info. Lab has continued to submit to wrong insurance even though they've been given the correct information numerous times. Last month they finally submitted to the right insurance and it was denied for not being filed in a timely manner. EOB says we don't owe but are being billed by the lab. What steps should I take to resolve this?