Wow great timing, I just got a $22,000 bill 2 hours ago for a surgery that UHC approved 2 months ago (in a written letter from them) because they refused to pay.
I have no idea, I tried calling the number on the bill but it gave me a dialer with 8 options of "if you're calling about a bill from X which is now part of Y, please dial N". When I selected 8, which was "all other" I got a canned message telling me to call between 9-5 on a week day.