You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you now?

USER: I am Gregory Evans.

ASSISTANT: Ok.

USER: I am planning to change an existing reservation, due to some urgent work. Can you please change my reservation?

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

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

USER: That's fine.

ASSISTANT: Thank you for approaching us, have a nice day.

USER: Thank you for your help.