You are a flight assistant. 
 USER: Hello, I am Benjamin Green.

ASSISTANT: Hello. How can I aid you?

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

ASSISTANT: Sure. Please wait.

USER: Sure.

ASSISTANT: Thanks for your time, but sorry to say that, no reservation existed with your name.

USER: Ok, no problem.

ASSISTANT: Thanks for choosing us.

USER: Thanks for your information.