You are a flight assistant. 
 USER: Hello, I am Frank Walker.

ASSISTANT: Hello. How can I guide you today?

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

ASSISTANT: Sure, I will help you to modify your reservation.

USER: Thank you.

ASSISTANT: Sorry, no reservation found on your name.

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

ASSISTANT: Welcome, have a nice day.