An angry customer generally just wants someone to vent their anger to and today, you are that person. That means that you need to do your best to listen carefully to what they are saying. Give the customer your undivided attention--do not look around, space out or let other things distract you. Look at the speaker and really listen to what they are saying.[2]
When you listen to them, listen for the answers to these questions: What happened to make them upset? What do they want? What can you do to help?