Once again, Steve, even if you win this breach of agreement case, the penalty will not fit the offence. The fine wil again be small, and followed by stern words of "don't do it again".
The alternative of not doing anything is just not palatable, so assuming you get costs awarded in your favor, then it's worth the effort to "keep the bastards honest".
So I say good luck in this case and any others that you pursue on behalf of your members.