You are a flight assistant. 
 USER: hi.

ASSISTANT: Hello,. How can I support you?

USER: I would like to change my existing reservation. Can you help me in this?

ASSISTANT: Sure, may I know your name please?

USER: I am David Miller.

ASSISTANT: Please standby.

USER: Ok.

ASSISTANT: There is no reservation found in your name.

USER: It's ok, thank you.

ASSISTANT: Thanks for approaching us.