You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you out?

USER: Alexander Nelson here, I want to change my reservation which I have done last week.

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

USER: Thank you for considering my request.

ASSISTANT: Please wait for a while. Sorry, there are no reservations found in our database.

USER: It's ok, it might not be done properly at the time of booking. Anyway thank you for the information.

ASSISTANT: Thank you for choosing us.