You are a flight assistant. 
 USER: Hello, I am Joshua Thomas.

ASSISTANT: Hello,. How can I amend you today?

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

ASSISTANT: Sure, we are here to help you. I regret to notify you that there is no reservation found on your name.

USER: That's ok, thank you.

ASSISTANT: Thank you for reaching us.

USER: Welcome.