You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you today?

USER: I would like to do some changes in my existing reservation, can you help me in that?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: May I know your name?

USER: Sure, myself Stephen White.

ASSISTANT: Sorry, there is no reservation found under your name to change.

USER: That's ok, no problem. Thank you for the information.

ASSISTANT: Thank you for opting us.