Sounds like true laziness on their part.
Why can't they go out and take their own photos? Pathetic.
I would take it also as a type of compliment. Usually if people copy you, they actually admire what you have done, but its still wrong.
I would learn from it and watermark all your great photos from now on.
And I would keep complaining to the site and even the person that posted them.
Also just looked at that site. Its Australian and your in the US. I am not sure how different copyright laws work between two different countries, maybe thats why they picked on.
One of their stores are not that far from me, so next time I swing that way will pop in and make a complaint as a fellow BYC Forum PEEP!
Maybe I could show them some muscle and poke them in the eye - naaaa just wanted to cheer you up.