One thing I would suggest is to meet with the principal instead of just emailing. You can send an email with a "I want to meet with you to discuss XYZ" but for something like this, I don't know I would leave it with just an email. Email is so impersonal in some ways, and people tend to misinterpret the emotions behind the email so easily. Especially for topics like this. (oh, and for all emails my husband and I send that are about areas of concern with our kids to anyone, we always make sure to cc the other spouse so the recipient knows it is coming from both of us).
The principal may or may not be aware of the extent of issues you had with the classroom and the difficulties you and your child had with that particular teacher. Sometimes the first time the principal is aware of how downhill things went is when they hear from the parents directly - it is not clear in your earlier posts if you have talked to the principal at all. Sometimes the teacher will cover up or understate the severity of the issue, or tell the principal a completely different spin on the issues than you expect.
I agree with Loy, in examining the goals you have for contacting the principal, and making sure it comes across without an accusatory tone. I noticed that when we came across as upset parents, the administration were more likely to just focus on agreeing with us and dealing just with the emotions, without really addressing the underlying concerns, but if we came in well prepared, and a calm exterior, they would be much likely to focus on the issues and working with us on finding ways to make our situation work. I wonder sometimes if you come across as "one of those parents", they are only going to placate you for however long it takes to get you to go away but just ignore whatever you say.
