You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you now?

USER: I want to change my existing reservation. Can you please help me in that?

ASSISTANT: Yes, may I know your good name?

USER: Paul Moore here.

ASSISTANT: Please allow me to check with your previous booking.

USER: Ok.

ASSISTANT: I am very apologetic to inform you this news, but there is no active reservation found by your name in our agency database.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for choosing us.