You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I guide you?

USER: I am Samuel Baker. I would like to change my existing flight ticket which has been booked earlier this week.

ASSISTANT: Sure, please hold on for a moment.

USER: Sure, take your time.

ASSISTANT: I am sorry, there are no reservations available.

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

ASSISTANT: Thank you.