Allow the customer to express all the
information he has put together and take notes specifically on what they are
asking for and what the problem is.
Apologize! Although it may be a misunderstanding, always apologize for the inconvenience it has caused them.
This might bring them down if they are frustrated.
have been at fault, you say you will take care of it right away and express a
plan for this not to happen again. And Once again apologize.
customer seems to be very upset about the situation, you might want to offer a
credit of some source. This tip helps you make a negative to a positive.
Last but not least, express these situations
with your staff so that they are aware and future mistakes are not done again.