You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

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

ASSISTANT: Sure, I am here to help you. May I know your name please?

USER: Myself Christine Walker.

ASSISTANT: Thank you. Please wait for a while, let me check your reservation status.

USER: Ok.

ASSISTANT: Sorry, I did not find any reservation by your name in our database.

USER: Not an issue. Thank you.

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