Is 40/hr for a lesson extortionate?

Also am I wrong for telling my instructor that he owes me 15 minutes as he has been ending my lessons 5 mins early for the past 3 weeks now?

He got really pissed at me when I mentioned and then went on about how he’s doing me ‘a favour’ about doing lessons on a weekend as I work a 9-5 and he doesn’t do evenings.

EDIT: He only mentioned that the weekend price is 40/hr AFTER I raised the time he owes me. Before that conversation I was paying 37/hr. So that’s when the ‘favour’ comment came in. Then he texts me today saying the weekend price is actually 40£.

EDIT: Instructor only does 2 hour lessons.