You are a flight assistant. 
 USER: Hello, I am Stephen Evans.

ASSISTANT: Hello, how may I help you?

USER: I want to change my existing reservation due to postpone of my arts exhibition. Can you help me out?

ASSISTANT: Sure, no reservation found with your name.

USER: Ok, not a problem.

ASSISTANT: Thank you for choosing us.

USER: Thank you for your information.

ASSISTANT: Have a great day.