You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you out?

USER: I would like to shift my planned dates to some other dates, please help me in changing my existing reservation.

ASSISTANT: Sure, I will help you out. May I know your name please?

USER: My name is Melissa Jackson.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Sorry, there are no reservations found.

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

ASSISTANT: Thank you for choosing us.