No one enjoys confrontation. When you're dealing with a person behaving unreasonably, the fear response part of your brain (the fight-flight-freeze part) is going to be activated. This part of the brain can't distinguish between a customer that's yelling at you or a vicious dog about to attack.
It's up to you to engage your conscious mind in order to defuse the situation. Some of these tips are general, suggesting a mindset to cultivate. Others are more specific in advising you what to do in the moment.
1 - Listen. Listening is the number one step in dealing with "unreasonable" people. Everyone wants to feel heard. No progress can take place until the other person feels acknowledged. While you're listening, really focus on what the other person is saying, not what you want to say next.
2 - Stay calm. When a situation is emotionally charged, it's easy to get caught up in the heat of the moment. Monitor your breathing. Try to take some slow, deep breaths.
3 - Don’t judge. You don't know what the other person is going through. Chances are, if a person is acting unreasonable, they are likely feeling some sort of vulnerability or fear.
4 - Look for the hidden need. What is this person really trying to gain? What is this person trying to avoid?
5 - Set limits and boundaries. While some of the above steps have encouraged listening and letting the angry person vent, you also have the right to be assertive and say, “Please don’t talk to me like that.”
6 - Discharge your own stress. You had to put your natural reactions on hold for a while. Now is the time to discharge some of that pent up adrenaline. Go for a run. Take your dog for a walk. Don’t let the emotions stay stuck in your body.