You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you out?

USER: I would like to spend some more days with my family, please help me in changing my existing reservation.

ASSISTANT: Sure, I will help you in changing the reservation.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: My name is Thomas Hall.

ASSISTANT: Sorry, there are no reservation found.

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

ASSISTANT: Thank you for choosing us.