You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: I am Karen Adams. 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 while I check for the status of your reservation.

USER: Sure, please take your time.

ASSISTANT: Sorry Karen, I have searched the database with your name. There is no reservations showing on your name.

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

ASSISTANT: Thank you, have a great day ahead.