Turn the unpleasant task of dealing with unhappy customers and grumpy coworkers into a game: You win by turning around their anger and making them happy.
When the other party says or does something negative, counter with a positive technique. Tell yourself, “There is no way this person will trap me into being counterproductive.” For example, if a member comes to the desk complaining that there are no towels to wipe down the machine he wants to use, find some towels and then go one step further and wipe off the machine yourself. Do it cheerfully, and you’ve turned this small customer inconvenience into a positive customer service connection. When you win, so does the other person. Source: 180 Ways to Walk the Customer
Service Talk, by Eric Harvey