You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I serve you?

USER: I want to change my reservation due to postponed of my Arts competition to other dates, so please help me.

ASSISTANT: Sure. May I know your name?

USER: Sure, my name is Ryan Miller.

ASSISTANT: Please wait a while.

USER: Sure.

ASSISTANT:  Thank you for waiting, but I am sorry to say that, there is no active reservation found with your name in our database to change it.

USER: No worries, thank you.

ASSISTANT: Thanks for choosing us.