You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I am Patrick Hall. My schedule examination dates are has been postponed, so I would like to change an reservation. Can you help me out?

ASSISTANT: Sure, please allow me a minute.

USER: Sure, take your own time.

ASSISTANT: Sorry, no reservation is found.

USER: That's fine. Thank you for your help.

ASSISTANT: Welcome.