You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How best I can I help you today?

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. Can I know your name to check the reservation status?

USER: Myself Thomas Anderson.

ASSISTANT: Thank you for giving 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.

ASSISTANT: Thank you for availing us.

USER: Thank you.