Sue the Dr. office for harassment. Then when they don't pay, send THAT to collections.
Seriously though, call the Dr. office billing dept. and ask them what's going on.
I know whats going on.
In short, wife was told by office that the doc. was in network, and then when app. was done they told her, that they made a mistake, and wanted to charge her.
After some back, and forth they settled on a lesser amount, and she got the bill stating paid in full, with a zero balance.
I was all pissed, and disputed the charge. After 2 weeks, I cancelled the charge back, deciding to just leave it.
The secretary got all upset at me, even though I canceled the charge back, and decided to send the bill to collections.