You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you now?

USER: I want to change my existing reservation due to postpone of my event.

ASSISTANT: Sure, can I have your  good name please?

USER: I am Jacob Young.

ASSISTANT: Sorry, no reservation has found under your name.

USER: No worries, thank you for the information.

ASSISTANT: Thank you for choosing us.