As sad as it is, your anger will probably not find the justice it deserves, i know your going to be really upset because your daughter is the most important thing you have. I can imagine how desperate your situation is because there isn't anyone responding how they should and there isn't any one individual to direct how you feel toward making it seem very hopeless.
Personally if its possible for you, consider what you can get out of this. If there isn't anything for you to get (ie; lawsuit if its what you want, protesting if its what you want etc) out of speaking still to the Witnesses and being in contact with the Congregation then cut it off, honestly it will eat away at you. I've put a lot of what i can put behind me away and already i've felt better - saying that however i acknowledge the hurt your daughter has gone through with yourself makes my issues with the Society seem like nothing.
If this is any consolation i am sure that the human part of these elders who don't respond probably do want to, but are trapped also.