Rant: Aveda Educator, mean girl

I go to the Aveda Institute here for my haircolour. I've loved the place: great product applied by skilled students under their Educator's supervision, for a third of the price of a 'name' salon.

Today I went there, drew the same student I had last month, but a new Educator. Educator informed me my roots would be touched up but she would not have the student apply colour through the ends (usually the last 5 or 10 minutes) because "your ends will accumulate too much colour. You can't do this every time."

I replied (calmly, civilly) that I would indeed like the ends done as a) I am red, it's fade-prone, b) in summer the sun lifts the colour more, and c) with short hair, I have the ends trimmed every 8 weeks.

(Note: I have been having my hair gooped for over 20 years and not once has a colourist not refreshed the ends. A fresh glowy red is one of the little pleasures of life.)

"Fine", she hissed, turned on her heel, did not appear (as the other Educators have) to check progress, and billed me $10 more than the preceding eight visits. When I asked her why, she said, "We used another tube of colour."

OK, I said, but the other Educators combed the colour through using one tube, what was different this time? "I can't speak for them", she said coldly. I said, "If you are adding a cost, I would like to be informed first." She repeated her "can't speak for the others" line so I said, "I understand your point of view, thank you" and left. We were in one of those pointless loops.

Now call me sensitive-wensitive (as we say in our family) but I found this woman as arrogant and defensive as I've ever seen. If I were making an inference, I'd say she was getting even. But who knows?

I have a letter to the Director of Education ready to send, giving appreciation where due (everyone I've met in the past 8 months) describing this incident, and requesting that upcharges be discussed with the client first.

I stopped short at naming her. But I have a hunch she already stands out.

What bugs me? Not the $10. Not even her need to be right. It was her hostility when I made my request.

Will I send it? I'm sleeping on it.

UPDATE: Thanks to your reminders to be diplomatic, sent a short letter emphasizing the usual marvelous service, did not name the Educator, and mentioned only her behaviour, not my inferences about her character or intentions.