How do I stay calm when a customer gets angry?

When someone turns their anger on you, your body reacts before your mind can. You freeze, or you push back, and either way it spirals. That is not a flaw in you; it is old wiring. A hostile face reads as a threat, and the threat response is fast and dumb. The skill is not to kill that reaction but to get a step ahead of it. Here is what helps: the angry customer is almost never actually angry at you. You are the face in front of a problem they hate. When you take it as a personal attack, you join the fight. When you see it as a person in distress, you can stay outside it and actually help, which is the thing that ends it fastest. So give yourself one move to reach for when it starts. Take a single slow breath before you respond, and lead with something simple: I hear you, let's sort this out. That breath keeps you from freezing or firing back, and those few words tell the person you are on their side. You are not letting them walk over you. You are refusing to spiral with them.