Please Keep Us Updated ThomasH !
I just read your thread and it resonated deeply with me.
I buy and sometimes trade handguns with a very large local gunshop. Quite a bit. We have a good relationship and I'm satisfied with the pricing I get.
When I trade, I return the original box, papers, handgun lock, instruction manual, extra mags, everything is returned just like brand new.
(I'm rethinking this. I don't plan to trade anything soon but if I do, I'll leave out some crucial component to insure that my pistol can't be sold as new.)
And the pistols themselves that I have returned and traded are just like NIB. Maybe 1000 rds put through them.
Recently I was at the aforementioned gunshop and saw one of my pistols for sale (a high end 1911) in the new gun case.
I carefully asked the retail help about it's status and no one could answer me.
This huge gun dealer was selling my pistol as new and at a price 200 dollars higher than the retail price of the pistol.
I'd noticed this before with another really fine 1911 I'd traded with them.
I suspect what the other posters have mentioned -- your pistol was a trade-in and not new.
The gunshop I'm talking about has a 30 day guarantee in addition to the manufacturer's warranty.
I'd suggest you demand your money back in cash.
Tell them you don't want to go legal but are prepared to.
If necessary, I wouldn't hesitate to mention that you have a lot of friends at a lot of different gun forums who love to read about good and bad gunshops.
Good luck, keep us updated.