You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you today?

USER: I want to change an existing reservation, so please help me in changing the reservation.

ASSISTANT: Sure, I am glad to help you.

USER: Ok.

ASSISTANT: May I know your name please?

USER: Myself Justin Taylor.

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: Sorry to say that, no reservation was found on your name to change.

USER: Not an issue. Thank you.

ASSISTANT: Thank you for choosing us.