You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello,. How can I best serve you today?

USER: I am Janet Hernandez, I just want to change my existing reservation.

ASSISTANT: OK, please wait for a moment.

USER: Sure,.

ASSISTANT: Thank you for waiting, Sorry to say there is no reservation on your name.

USER: OK, Thank you for your information.

ASSISTANT: Thank you, have a nice day.