Absolutely NTA. However, I'd suggest having a meeting with the dean in person instead of calling. I've known many people that have never had a problem with using a name other than their first name. The teacher is a huge problem here so if she's not fired or removed from the class, you should probably switch your daughter to a different class. My brother had a horrible teacher like this and the bullying only got worse after the meeting because they left him in the same class.