Ruslara, we had real problems with ds (7) teacher last year. Thought our boy had gone off the rails from the tone of the meeting, when in actual fact there seems to be a pattern developing - loves wee girls, not so keen on boys. (Not being an adoring mother, but only worked this out after speaking to other mums and seeing her behaviour at school events.)
She kept coming out with statements like 'unacceptable', 'unreasonable', 'inappropriate' behaviour. DH and I kept pushing her for examples, and then we found out that it was talking in class, and having a carry on when lining up to come back into school after break - hardly worthy of expulsion.
She hated being pushed for examples, but I didn't really care about that, only wanted to get to the bottom of it. After we found out what she was meaning,we went in heavy with the charm offensive 'wanting to work with the school', 'trying to back her up by giving consistent messages at home and school', etc. Very difficult to be so nice to someone I really didn't like as a person, and felt quite sorry for ds to have to put up with her.
We also kept in touch with the school to prove that we meant what we said. She never, ever said anything positive without following up with a negative, but we still just kept smiling and let her know we were as much on her case as we were on ds's. DS confidence took a real battering, but on the plus side is with a fabby teacher this year, has moved up to the top stream for reading. Although I can well imagine he's still a monkey, is just flourishing under a really positive, warm, lovely woman as a teacher.
Sorry, this is a really long posting, but I can understand your frustration. Another way to look at it, however, is that maybe your DD is getting on really well and she's not got anything much to say about her?