[competentone]

Reading your "transcript" of the conversation (with a bias most probably in your favor), it sounds more like you are the one being pretty unreasonable.

At the very least, your transcript makes you sound quite unprofessional. Your "seething with rage" emotion over the cancellation says a lot about you.

I don't know what sort of business you are in, but shifting one's schedule -- and sometimes canceling appointments (which involves putting one person in front of another) is a constant factor in many businesses.

It can sometimes be frustrating, but not anything one should fly into a rage over -- or be calling people "a**holes" over.

Get a grip.