You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

USER: I want to change my existing reservation, because my college annual day is postponed. Can you help me?

ASSISTANT: Sure, may I know your name please?

USER: Ok, my name is Patrick Clark.

ASSISTANT: Please wait a while.

USER: Ok.

ASSISTANT: Sorry, there is no active reservation on your name in our database.

USER: Ok, no problem. Anyway's thank you for your information.

ASSISTANT: Thank you for approaching us.