You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Christopher Roberts.

ASSISTANT: How can I help you out?

USER: As my plans to visit Denver has postponed, can you please help me in changing my existing reservation to Denver?

ASSISTANT: Sure, we are gleeful to help you. Please wait a minute.

USER: Sure, I will wait for your response.

ASSISTANT: Thanks for waiting, there is no active reservation on your name in our records.

USER: Ok, not an issue. Thank you for providing information.

ASSISTANT: Thank you for contacting us.