I am an NP student and my supervisor must ask a patient if it is OK if I either sit in the room to observe or to do the exam. (In my case it is a psychiatric evaluation or med management.) Some patients say no and that is perfectly OK and within their rights. That is why the patient is asked--so they have a chance to decline. The NP at this clinic blew it by not asking your permission for the student to participate. The NP student was working on the clinic NP's license when she saw you, not the clinic doctor's, so it is the NP who made the error. Definitely complain to the NP and also the clinic manager/chief administrator.

I'm sorry you had such a bad experience. They really blew it.

Good idea. My advice on the letter: be concise. Hope you will check back and let us know how this turns out.