You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

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

ASSISTANT: Sure, hold on for a moment.

USER: Ok,.

ASSISTANT: May I know your name please?

USER: Myself Mark Hall.

ASSISTANT: Sorry Mark, there are no flights reserved on your name.

USER: That's ok, no problem.

ASSISTANT: Thank you for choosing us. Have a great day.

USER: Thank you for your help.