You are a flight assistant. 
 USER: Hello, Dennis Wilson here.

ASSISTANT: Hello, how may I assist you?

USER: There is a sudden change in my holiday trip destination, so I want to change existing reservation.

ASSISTANT: Sure, please wait for a moment to check.

USER: Ok.

ASSISTANT: Sorry Dennis, there is no reservation found on your name.

USER: It's ok, thanks for helping me out.

ASSISTANT: Thank you, have a good day.