You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: I want to change my reservation which I had booked on the name Christopher Green. Can I help me?

ASSISTANT: Sure, I will help you.

USER: Ok, thank you.

ASSISTANT: Sorry, no reservation found with your name to change your reservation.

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

ASSISTANT: Welcome, have a safe flight.