Although usually levelheaded, there have been a few times when I have indeed lost my gruntles. I expect that others have, too, usually when arrangements one thought were clear, precise, and confirmed, turn out to not be so. (An incident at a Holiday Inn comes to mind.)
In such cases, thought I might have said unkind things to the company's representative, it's never been a personal thing. It's the company I'm angry at. And at that moment in time the company has hired YOU to be their interface, so it is your unfortunate lot to have to listen to me.
Is that fair? -- no, of course not.
Do I later regret what you had to endure? -- surely.
But that's not the point.