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

ASSISTANT: Hello, how may I assist you?

USER: I need to change my existing reservation due to delay of my project submission. Could you please help me?

ASSISTANT: Sure, please wait for a moment.

USER: Sure.

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

USER: No worries, thank you for the information.

ASSISTANT: You are welcome.