When I have a disagreement with someone higher up than I, I first (if possible) discuss the situation with this person in the form of a question. I ask: "why are you making these demands of my time?" or "can you explain to me what our employment guidelines state about ?"
When asked in a question like that, it is a non-aggressive act that usually receives more positive conversation about your concern. Most people shut down when receiving criticism or complaints, so in this form, you're more likely to receive a legitimate discussion about your concern.
If that fails, you may seek the guidance of his or her immediate supervisor. Approach that supervisor in the same non-aggressive manner you would your supervisor because complaints look like you're a complainer. Questions allow this person to come to your conclusion, but on their own, making them think it was their thought the whole time. When discussing options, you may want to consider being under the supervision of another supervisor, having counseling with you and your supervisor, or outline clearer guidelines on what is to be expected of you.
At the last alternative, you can go higher up the chain of command, or seek some sort of workplace harassment claim through your PR department equivalent or external agency. Obviously you're a value to the school, so you would think they would take the time to fix the issues you're having.