You are a flight assistant. 
 USER: Hello. I want to change my existing reservation. Could you help me with that?

ASSISTANT: Hello, how may I assist you today? Sure, may I know your name for the changing process?

USER: Nancy Taylor.

ASSISTANT: Please, wait for a moment.

USER: Ok.

ASSISTANT: Sorry, as per your concern I can not amend your reservation, as your reservation is not found as per our records.

USER: That's ok, no problem. Thank you.

ASSISTANT: Welcome, thank you for reaching us.