I just hate to hear stories like this. Unfortunately these days you hear more and more and not enough of the good ones!
As a teacher, I think you should have tried to talk to the teacher(s) first despite how unaproachable I am sure they are. But that is obviously hind site now. At this point, I would go ahead and respond and say something like:
I am really sorry I didn't talk to you first. Being with the tone you spoke to the children I was concerned you wouldn't listen to my input either. However, you're right I should have come to you. As for the problem, what can I do to help? I know things can get so busy and hectic in the classroom with little planning times and so many children to care for. Despite how this has all gone down, I hope we can try to work towards a positive solution to the problem.
Plus, knowing teachers and the 'type' they sound to be, they are probably all whispering about it and going to show each other your response. Unfortunately, parent reputations do follow your kids. After your email I hate to say it but again as a teacher, the best thing is to let it go for awhile. They have heard your input. The pricipal knows about it, so it has been adressed. Now that they know your daughter tells you what happens, they are going to think twice about what and how they say things. But, the more you push it the more ackward it will get. Time away and/or time ignored will probably do some good. If she responds back to your email, then just say, okay thanks! that's it. No matter what she writes.
If something else happens or behavior continues. Then perhaps you can readdress the principal, saying Yes I have talked to the teachers and it wasn't fixed. What have you also done to address the issue? See what he says. If nothing, then say I would like to be moved to another track.
Blessings,
Amanda