You are a flight assistant. 
 USER: Hello.

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

USER: Can you please help me in changing the existing reservation as my business meeting got postponed?

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

USER: Thank you.

ASSISTANT: Please let me know your name to check the reservation list.

USER: I am Karen Jackson.

ASSISTANT: Ok, please wait a minute I will get back to you with the present status.

USER: Ok.

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

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

ASSISTANT: Thank you for approaching us.