You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Emma Martin.

ASSISTANT: How may I help you?

USER: I am planning to change an existing reservation.Can you help me out?

ASSISTANT: Sure, wait a second please.

USER: Sure.

ASSISTANT: Sorry to say, no reservation found on your name. Thank you for choosing us.

USER: That's fine. Thank you for your help.