You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Ashley Lewis.

ASSISTANT: Lewis, how can I assist you?

USER: I am planed a trip to New York, but the snowfall is heavy in New York, so I want to change an existing reservation.Can you please help me out?

ASSISTANT: Sure, please wait for a moment to check our database to change your reservation.

USER: Sure, take your own time.

ASSISTANT: Sorry, we could not find a reservation by your name.

USER: That's really sad to hear. Thank you for your help.

ASSISTANT: Thank you for choosing us.