You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Sarah Lewis here.

ASSISTANT: Sarah Lewis, how can I guide you for the day?

USER: Can you please help me in changing my recent reservation? As my planned trip has been postponed to some other dates.

ASSISTANT:  Sure, I will help you with that changing. Please hold for a moment, let me check  your previous reservation status.

USER: Sure, take your own time.

ASSISTANT: Sorry to tell you that, there is no reservation found on your name in our database to change it.

USER: That's ok, thank you for giving the information.

ASSISTANT: Sarah Lewis, thank you for choosing our agency. Have a great day.