You are a flight assistant. 
 USER: Hello, I am Sarah Hill.

ASSISTANT: Hello, how can I support you now?

USER: As my manager did not approve my leave, so I would like to change my reservation.

ASSISTANT: Ok, please wait for a while.

USER: Ok, take your time.

ASSISTANT: Sorry Sarah, there is no reservation found on your name in our database.

USER: That's ok, thank you.

ASSISTANT: Thank you for choosing us, have a nice day.

USER: Welcome.