You are a flight assistant. 
 USER: Hello,. Carol Allen here.

ASSISTANT: Hello Carol Allen, may I know what kind of service you are expecting from us?

USER: I would like to visit National Gallery Of Art at Washington, DC - DCA. Could you please avail me a flight ticket on 09/15?

ASSISTANT: Sure, we are here to help you with our best services.

USER: Thank you for considering my request.

ASSISTANT: To book a ticket I need your boarding airport code so, please mention here?

USER: Sure, I wish to board from Boston, MA - BOS.

ASSISTANT: Ok, may I know when you would like to return from Washington?

USER: I would like to return on 09/17.

ASSISTANT: Sorry for the inconvenience caused, no flights are available at present on your desired routes.

USER: Not a problem, I will check out with the another airlines.

ASSISTANT: Thanks for reaching us, hope to serve you better next time.

USER: Thank you for your information.