Keep a paper trail of everything, from emails sent relating to your service to any fees paid out to contractors or anytone else working under/for you w/ the project. If they make a stink out of it, I would suggest hiring a lawyer to represent you (we have one that we have on retainer -- tends to be cheaper this way). If you don't have the funding for this, you could always ask them to rename theirs and maybe they'll comply in good faith if you prove you had your name and whatnot first... or the last option would be to follow chandrab and just rename your product... it'll keep a stink down w/ the other company and won't be a costly blackhole to throw money you could have put into marketing the new name.
