You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I'm John White, could you do me a favour in reserving a plane ticket to Washington, DC- DCA?

ASSISTANT: Sure, I will help you with that. Can I have your travel dates please?

USER: My travelling dates are from 09/28 to 09/30.

ASSISTANT: From which airport do you want to start?

USER: I would like to start my journey from Houston, TX- IAH.

ASSISTANT: Ok, please wait a moment.

USER: Ok.

ASSISTANT: Sorry John, there is no flight available to you on your dates.

USER: That's ok, thank you for the information.

ASSISTANT: My pleasure. Thank you for choosing us, have a great day.