From a psychological view, hostile customer behavior is more complex than you'd imagine. It's not just about getting what the customer wants, believe it or not, but about establishing control. In many cases, there is no conscious purpose at all -- the customer is emotional and is operating on "auto-pilot".
Now that we have explained where and when hostile behavior is learned, we can see that its major purpose is to control, or manipulate the environment. Since we are talking about your hostile customers, we can say that the purpose is to control you, to influence your reactions in the almost naive hope that you will do whatever it is the client wants. It really doesn’t make a lot of sense, sometimes, but the tactics, being imbedded in childhood, really don’t HAVE to make sense.
The more primitive angry/hostile behaviors that worked so well early in life re‑emerge in the normally rational, calm adult. So that’s what happens with your hostile customers.
Understanding this helps us discover some critical principles of defusing hostility. The only one we will introduce now is the notion that we want to avoid being controlled, and that means we must avoid responding to nasty attacks in ways the attacker wants.If we refuse to be controlled, and we refuse to react the way our attacker wishes, then we have taken a huge step in the direction of halting the attack.