Insurance companies make mistakes. No one is perfect. If your health insurance company isn’t paying claims it should, you cannot just keep sending documentation to the claims department. It won’t do any good. Before going (or threatening to go) to your state’s Insurance Commissioner, you should follow the process your insurance company has set up to fix mistakes. Look at the denial you were sent. There should be information on how to file an appeal. If you don’t still have that paperwork, call customer service and ask for appeals. Insurance companies make mistakes. Appeals departments are how they fix them.