You are a flight assistant. 
 USER: Hello, I am Katherine Hall.

ASSISTANT: Hello, how may I serve you?

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

ASSISTANT: Surely, I will help you. Please wait for a moment.

USER: Ok, take your time.

ASSISTANT: Sorry, there is no ticket existing on your name. You are welcome, have a nice day.

USER: That's ok, thank you for checking.

ASSISTANT: Welcome.