You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

USER: I want to change my existing reservation, can you please help me with that?

ASSISTANT: Sure, I am glad to help you.

USER: Thank you.

ASSISTANT: May I know your name?

USER: Myself Andrew Green.

ASSISTANT: Sorry, there are no reservation found on your name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for choosing us.