You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Due to some issues I would like to change existing reservation, can you help me ?

ASSISTANT: Sure.

USER: Check the details on Stephen Wright.

ASSISTANT: May I know your name for changing your reservation? Let me check.

USER: Ok.

ASSISTANT: Sorry Stephen, no reservation found by your name.

USER: Thank's ok.

ASSISTANT: Thank you for contacting us.

USER: Thank you for your information.