STAY AWAY - Had a visit over a year ago, just now ...

STAY AWAY - Had a visit over a year ago, just now received the bill. They forgot to bill my insurance company and now I AM responsible to pay because it's too late to submit to insurance now. Talked to two different people in their billing department and they both acted like I did something wrong and were pointing the finger at me. I have been a patient of theirs for over 20 years, but not after this. I have always timely paid and this is how I am treated? Obviously if I was treated like this by two different employees, this type of treatment is standard with their practice. I WILL NOT support a company like this.