It is probably a case where the insurance hasn't paid on some claims yet and the bill is showing the balance that hasnt been paid yet, including what the insurance hasn't sent them a check for. Don't panic about it. Talk directly to the billing people to find out what is going on. I had a couple of cases where that happened. No big deal. Just took a few weeks for the insurance company payment to come through their office. Another case, they had filed and for some reason the insurance company had overlooked it. Just took a couple of phone calls to straighten out.