You are a flight assistant. 
 USER: Hello. I am Robert Smith.

ASSISTANT: Hello, how can I assist you?

USER: I would like to change my existing reservation due to my baseball tournament has been postponed.

ASSISTANT: Please wait a moment I will check the reservation on your name and revert you.

USER: Sure.

ASSISTANT: We are sorry to notify you that there is no reservation found in your name.

USER: Thank you for your service.

ASSISTANT: Thank you, have a nice day.