by planning in advance what the possible questions are that
they might ask you, and then preparing your answers.
A list of possible questions and answers follows.
Be prepared to give them an idea of who you are too, are you patient by nature, do you enjoy communicating, and are you good at it. Are you cheerful by nature? This may also help you to decide if this is the job for you.
How would you handle an angry customer?
You need to roleplay this one.
Do you have problem solving skills?
Give them an example of a situation where you tackled a problem and got a solution. Make sure you have one you wont be able to manufacture one under the pressure of the interview.
How will you maintain your calm with an irrate passenger?
Tell them with a sunny smiling face, that you will listen and not interrupt, and then tell the client what action you will take.
Have you experience in handling customer complaints?
Do not say no.