You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Larry Scott.

ASSISTANT: How can I help you now?

USER: Actually, I want to change an existing reservation, can you help me out?

ASSISTANT: Sure Larry, I will help you. Please wait a moment.

USER: Sure.

ASSISTANT: Sorry Larry, no reservation has found with your name.

USER: That's fine.

ASSISTANT: Thank you for consulting us.

USER: Thank you.

ASSISTANT: Your welcome, have a good day.