I was given some great advice in regards to kids not doing what is asked of them. You need to give her a choice. Give her 2 choices that she can chose from and both need to be something you will be happy with and something that will complete your request. Does she want to apologize to the teacher as you requested face to face?....or does she want to do it with the principal and the teacher....you know something to this effect. Maybe if you are willing to give in a little bit on the face to face and give her the option of face to face or in writing... I have found the choice option works wonders with my oldest who as soon as she is given a task is defiant.