You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you out?

USER: I want to change my reservation as I have to prepare for my exam, could you please do that for me?

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

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: May I know your name please?

USER: My name is Melissa Thompson.

ASSISTANT: Sorry, there are no reservations found in our database.

USER: Not an issue, anyway thank you for checking.

ASSISTANT: Thank you for choosing us.