You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I guide you?

USER: I am Justin Walker. I would like to change my reservation which has been booked earlier this week.

ASSISTANT: Sure, please hold on for a moment, let me check.

USER: Sure, take your time.

ASSISTANT: I am sorry, there are no reservations with your name. Thank you, have a good day.

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