Something had to be said because he needed to be told that his behaviour was unacceptable. Actually, I told him that myself, but he wasn't interested in my opinion.
Perhaps I was a little hasty. Maybe his feet were hurting or his dog had just died. No matter; you don't take your troubles to work, especially when you're dealing with the public. Anyway, lovely Lisa at the Customer Service desk took my concerns seriously and offered me coffee and cake in compensation. I was entirely satisfied by the way the matter was handled.
Then I came home to write a yoga lesson plan and my book of Buddhist reflections that I sometimes turn to for inspiration fell open on this:
Never speak harsh words, for once spoken they may return to you.
Angry words are painful and there may be blows for blows.