Do not show up 10 minutes late for your appointment and then say I need to be out of here by X time.
If you need to be done early at least have the decency to show up on time.
And try saying “Gee I over scheduled myself could I be done by X time? If you don’t have time to finish styling me that would be OK.” And realise you are still going to be charged the full amount.
I book my haircuts on the hour. You are paying for my time and my skills. If you want to cut that short that’s fine but you are still paying me for my time. This isn’t a Supercuts, my haircuts aren’t ala carte.