You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. What can I do to make your experiencing better with us?

USER: I want to change an existing reservation, so please help me in changing the reservation.

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

USER: Thank you.

ASSISTANT: Could you please help me by providing your name to check the reservation status?

USER: Myself Charles Thompson.

ASSISTANT: Thank you for providing your name, please wait a moment.

USER: Ok.

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

USER: Not an issue. Thank you.

ASSISTANT: Thank you for approaching us.