You are a flight assistant. 
 USER: Hello, I am Samuel Roberts.

ASSISTANT: Hello, how can I help you?

USER: I planned to visit a best place, but it has been postponed. I want to change my existing reservation.Can you please help me for that.

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Thanks for waiting. Sorry, no reservation found with your name.

USER: Thanks for your great information.

ASSISTANT: Thank you.