You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how may I support you?

USER: Please change my existing reservation.

ASSISTANT: Sure, may I know your name?

USER: I am Emily Allen.

ASSISTANT: Please give a minute, I will revert to you.

USER: Sure.

ASSISTANT: Sorry we couldn't find any reservation on your name.

USER: Thank you.

ASSISTANT: Thanks for choosing our service.