You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: As my leave got extended, I want to change my existing reservation. Can you help me out?

ASSISTANT: Ok, may I know your name please to change your reservation?

USER: Sure, my name is Katherine Hernandez.

ASSISTANT: OK Katherine, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry Katherine, there is no reservation found as per your name to change your reservation.

USER: That's ok, thank you.

ASSISTANT: You are welcome.