You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I be of your assistance?

USER: I have to change my existing reservation, because my final examination is got postponed. Can you help me?

ASSISTANT: Sure, I'll help you in changing an existing reservation.

USER: Thank you for accepting my request.

ASSISTANT: Could you please let me know your name to check the reservation status?

USER: Yes, I am Lisa Scott.

ASSISTANT: Ok, please wait a moment.

USER: Sure, take your own time.

ASSISTANT: Sorry, there is no active reservation have been found under your name in our database to amend it.

USER: That's not an issue.

ASSISTANT: Thank you for choosing us.

USER: Anyway's thank you for your help.