Appeal it. In writing. When I was admitted to a hospital my insurance (Kaiser) didn't take because I was in another state, I had to have emergency surgery. Kaiser fought me. They wanted me to fly back to my home state. Ha! Yea right ....All the darn office managers from the various drs threatened to ruin our credit, said pay it and they'd reimburse me, blah blah blah.
I kept excellent records, called once a month (all TWELVE of them), and sent copies of my correspondence with my insurance to all the office managers. Really p***ed them off too. :D
Nine months later, I won.