You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, may I know your name?

USER: I'm Amy Smith.

ASSISTANT: Amy Smith, tell me how may I help you?

USER: I want to change my existing reservation, because of my postpone of my exam. Can you please help?

ASSISTANT: Ok, just hold on, I will check your previous reservation.

USER: Sure.

ASSISTANT: I am sorry Amy Smith, there is no reservation found with your name to change.

USER: Ok, that's fine.

ASSISTANT: Thank you for approaching us.

USER: Thank you, for your kind information.

ASSISTANT: You are welcome.