You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Mark Hall.

ASSISTANT: How may I guide you?

USER: I would like to change my reservation as I  am moving to business trip, can you please help me out?

ASSISTANT: Sure, may I know your name for checking purpose?

USER: I already mentioned above.

ASSISTANT: There is no reservation obtained in our data base to modify the ticket.

USER: Ok no problem, thank you for your services.

ASSISTANT: Thank you for approaching us, have a nice day.