You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I guide you?

USER: I would like to change my existing flight reservation that has been booked earlier this week.Could you please help me in re-modifying my dates in the reservation?

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

USER: Sure.

ASSISTANT: I am sorry, there are no reservations with your name. Can I know your name?

USER: Myself Anna Hall.

ASSISTANT: Thank you.