I got caught between a hospital and a collection agency once; I had insurance but the hospital did not note it right for themselves or something so turned me over to a collection agency; I told the collection agency and they said "there's nothing we can do", I told the hospital and they said they'd take care of it and did not so I kept getting calls, etc. I worked for a large non-profit that had a lawyer I knew well so I went and asked him what to do and he told me what to write in a letter, detailing everything to the legal department of the hospital and it was like magic, everything got quiet