You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

USER: I am planning to visit Dallas, will you help me in booking the flight ticket from DCA to DFW?

ASSISTANT: Sure, could you please share your departure and arrival day?

USER: My travelling dates are Aug 17 and Aug 19.

ASSISTANT: Ok, could I have your name please?

USER: Myself Rebecca Martinez.

ASSISTANT: Ok, do you need direct or connecting flight?

USER: I need a connecting flight.

ASSISTANT: Ok, may I know your class preference?

USER: I always prefer business class.

ASSISTANT: Sorry, there is no flight with your request.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: You are welcome, have a great day.