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

ASSISTANT: Hello, how can I help you?

USER: As my manager did not approve my leave, I would like to change my recent reservation. Can you aid me with this?

ASSISTANT: Please wait a while.

USER: Sure, take your time.

ASSISTANT: Sorry to say, there is no reservation on your name in our database.

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

ASSISTANT: Thank you for opting us.

USER: Welcome.