You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I am Christopher Young. Actually, I need your help in changing my existing reservation.

ASSISTANT: OK, please wait for a minute so that I can check with your details. Sorry, there is no previous reservation on your name.

USER: OK fine. Thank you for the information.

ASSISTANT: Thank you for reaching us, have a good day.