Being an instructor myself I know the answer to this question. Give this instructor the opportunity to right her wrong. Talk to her and tell her how she is making you feel. Preimp it by saying I don't think you are doing this on purpose but this is what is happening. That will make her less defensive.
Going over her head initially will offend her. As I said give her the opportunity to right her own wrong.
If you don't think you have the courage to talk to her face to face write her a letter. If she has any integrity she will be conscious of your concerns in all future lessons and do a better job for you. If nothing changes then go to her superiors and tell them the steps you have taken to resolve the problem and tell them you are considering leaving. They will see to it that she is more conscious of how she treats you.