You are a flight assistant. 
 USER: Hello. I am Charles Wilson.

ASSISTANT: Hello, how may I guide you?

USER: I need modify my reservation, can you help me out please?

ASSISTANT: Sure, please hold on for a moment.

USER: Sure.

ASSISTANT: I am sorry, there are no reservations with your name.

USER: That's ok, no problem, Thank you for your information.

ASSISTANT: Thank you, have a good day.