You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Andrew Scott.

ASSISTANT: Andrew Scott, how can I aid you today?

USER: Can  you please book a flight ticket from OAK to DCA?

ASSISTANT: Sure, I am here to help you. May I know your travel dates please?

USER: Thank you. I have planned my travel dates as Sept 04 and Sept 06.

ASSISTANT: Ok, do you have any requirements?

USER: I would like to return in afternoon time so please make sure that.

ASSISTANT: Ok, hold on for a moment. Let me check the best available flight for you.

USER: Sure, take your time.

ASSISTANT: Sorry Andrew Scott, there are no flights available on your requested dates.

USER: Oh! It is sad to hear. Anyway, thank you for your time.

ASSISTANT: Welcome, thank you for choosing us. Have a great day.

USER: Most welcome.