Why did you go to the ER. This isn’t an emergency. You should have seen a regular doctor. An emergency is if you break a bone, or cut your leg off, get shot, mvc, trauma. I have worked in an ER for 9 years and we see people like you everyday. The thing you must realize is that the ER was probably short staffed and over worked with hundreds of other non emergent patients. If people like you and them would go to a regualr docor instead of an ER then they staff there could provide better care for those who really need it.

You have nothing to lose by writing to them and telling that you won’t pay for their sloppy work. But I don’t think you would win in court.