You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: My trip was postponed, so please help me to change my existing reservation.

ASSISTANT: May I know your name for changing reservation?

USER: My name is Stephen Parker.

ASSISTANT: Please wait a moment.

USER: Ok.

ASSISTANT: Sorry Stephen Parker, no reservation found on your name.

USER: Its ok, thank you for your support.

ASSISTANT: Your welcome.