You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you at this moment?

USER: I need a flight ticket booking from IAD to HOU to attend a client meeting, can you please assist me with booking?

ASSISTANT: Sure, I am here to help you with that. Can I know your planned trip dates?

USER: Thank you and I would like to depart on Sept 2nd and I will arrive back on Sept 4th.

ASSISTANT: Do you any other preference?

USER: I have planned to travel in business class flight with a single limit in my travelling.

ASSISTANT: May I know your name?

USER: I am Sarah Lopez.

ASSISTANT: Please wait for a minute.

USER: Sure, I don't mind to wait.

ASSISTANT: Sorry to inform you that. there are no flight's available based on your journey details.

USER: Sad to hear that one form your side, anyway thank you for you quick help and providing the information.

ASSISTANT: Thank you for reaching us.

USER: Welcome.