Non-legal solutions are the way to go. If they don't work:
You can probably get some sort of legal answer by posting
to legal usenet groups.
You can probably get a quicker and more understandable
legal answer by reading:
and perhaps the book they're flogging.
If the non-legal solutions don't work, you might want to
invest a couple of hundred bucks in having a lawyer send
a "nasty-gram." In the print world this works 95% of the
time. I suspect it's not quite so successful on the Net,
where people don't realize that, yes, Virginia, plagiarism
is a civil offense.
I trust you copied the evidence to file.
"SOURCE CODE UNAVAILABLE", huh? Unfortunately the right
scroll bar tells how long a page is...