Having raised a daughter through the public school system, I feel your pain. Not that these things can't happen in a private school either, but it just all feels unfair. On the same token, there are some great teachers out there, I remember them myself!
K - 2, I had the most wonderful nurturing teachers. I felt like I was learning and enjoyed school. When I got to 3 - 5, I hated school because my teacher all seemed too annoyed for us. I was paddled many of time and if you were caught day dreaming a chalk filled eraser was thrown at your head while the teacher belittled you for not knowing an answer or keeping up. Of course, these were the days when all this was allowed. But really, a chalk filled eraser...chalk dust in the lungs can cause cancer. With all that, I can remember feeling jealous because someone else got the teacher I really wanted. I did the worse in those classes that I hated the teachers.
Back to my daughter, I was told my daughter didn't listen, she was crawling under tables, disruptive, the whole bit. My discoveries over the summer is that she had a lazy eye. The doctor asked if I had such complaints in school and I was amazed she knew. It turns out, the eye tires from going from the small lined paper to the chalk board and then because they can no longer see, they can no longer concentrate...then the attention goes. We did 24 weeks of eye therapy and she got a pair of glasses. She turned out to be normal. Tadaaaaa!
Sometimes the problem is not right up front, nor what they think.
You have to be careful not to fight with these type teachers too much because they can tend to take it out on your children. Your child is there with them all day and you are not. Be careful with your replies to them and your tone, yet stand up for what you believe in.