You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I would like to Change my existing reservation due to not availing of leave from my office. Could you please help me?

ASSISTANT: Sure, may I know your name?

USER: I am Stephen Lewis.

ASSISTANT: Sorry, there is no reservation found on your name.

USER: No worries, thank you for the information.

ASSISTANT: Thank you for choosing us.