Raising a well-mannered child

Can you tell me how it is possible? Is there a way to do it without going insane? Because I would really like a trick or two.
Yesterday K's teacher told me that she got in trouble at school for talking back to teachers. Apparently, she was told to do something and yelled "NO!" to the teacher. What? Am I raising a monster? So, as is our rule, when she has a "bad day" at school, she gets no movies in the evening. She knows this rule. It's something we have been very, very strict on. It always causes an nightmare, but we hold to it... always. I also told that today she needed to go in and apologize to her teacher.
Hopefully all of this will work!