First, was this a "new in the box" advertised firearm? Were you able to examine it at all? Could you rack the slide? So let me break it down.
NIB - if you feel this was a used firearm sold as new, than you could report it to the Attorney Generals office. False adverting and selling a used firearm as new are both frowned upon, the second more than the first. ATF could also be notified if you think they are selling used firearms as new. They could potentially lose their license.
If it was not new and you were able to rack the slide, most of the wear should have been noticed. At least the brass on the breech face and dirty barrel. Rail wear may have been difficult to gauge on that model, not sure, not too familar with it.
Now I diffently understand your position and do feel their policy is wrong, but a bit more information would be in order to make an informed decision as to what your course of action, if any, is left for you to pursue.