No kidding, I would be PISSED. I would publicize the crap out of it... and, yeah, obviously seek damages and/or royalties.
Don't think that some "15 minutes of fame" (acknowledged or otherwise) makes it worth it for your art and creativity to get pillaged by someone else. If you want to be famous, you can do it - it just requires some dedication in the long term.
There's that retarded saying, "good artists copy, great artists steal"... That is pure BS. Great artists create from the heart and soul, completely from within. Whoever came up with that quote is completely misguided and frankly not remotely worthy of any recognition as a professional, ever. Of course, it was probably coined by someone who would do anything for their 15 minutes of fame, regardless of moral/ethical sound-ness.
Yeah, my $0.02 CDN...