How do you manage a customer if he or she get upset or angry? what will you do to become her/him calm and feel him relaxed?

direct her/him to the office to where she can sit and offer glass of water, then after few minutes ask, inquire about what makes her angry or upset. listen and identify the root cause of her complaints then address the issue or solve according to the standard as set by the company rules.

I deal with tactfully, intelligence and speed and agility earned him the students quickly