You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Brandon Moore here. I would like to change my destination airport code, please help me in changing my existing reservation.

ASSISTANT: Sure, please wait a minute. Firstly, I have to check your existing reservation.

USER: Sure, take your time.

ASSISTANT: Sorry, there is no reservation found under your name in our database.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Most welcome.