That sort of thing is annoying, and I've had the same thing happen; but unless it's an ongoing, wholesale plagiarism there isn't much point in worrying about it. You could always state your case in the newsletter, though, with a note about giving proper acknowledgement if material is to be reproduced.

One small piece of comfort; whoever built the site is such a sad bastard that they actually used MS Word to generate the code, which explains the hideously ghastly design, the fact that it uses frames (best avoided nowadays; admittedly I administer one framed site, but I inherited it) and that it's more-or-less unreadable in older browsers. They ought to employ a professional.