Hi, W. --
That's such a terrible and frustrating situation that you're in. I really feel for you.
Well, first of all, the problem with volunteer organizations is that they're run by volunteers ;)! If being a troop leader were this woman's job, you could have her cited, demoted, or pay docked! If she won't respond to your contact, it seems there's little you can do... I mean, her behavior, if it's intentional and not just a result of her being overstressed and overtaxed with things to do, would indicate she would certainly not be a very good troop leader for your daughter.
Perhaps, if one more direct attempt to get her attention doesn't work, you could appeal to the person in the organization directly above her for intervention OR maybe for referral to another troop that is more conscientious and fair. I'd definitely want to see my daughter involved in a troop where she'd flourish and be led by someone who cared about her development and enjoyment.
So, that would be my second suggestion -- see what other troops are in the area and involve her with one of those instead. That way, she'd not only have the friends she'd made at school but also friends from another area via her troop. Maybe that would be neat. I don't know how the whole thing works, but it seems that could be an alternative.
I wish you all the best!