I work in customer services for a well known retailer.
Today I spent an hour listening to a man verbally insult me. No swearing but just completely unnecessary personal insults about my intelligence, my personality, my experience, the fact I have a cough, the fact all I said was 'mmm' (he didn't let me speak).
All because he didn't like a policy that I didn't make and can't change.
He really was the most unpleasant person ever and ruined my afternoon!
I'm good at my job, fair, polite and firm, experienced but he really got to me today 
The large glass of wine I'm drinking is helping!
Why do some people resort to such unpleasantness?