You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you now?

USER: Cynthia Smith here. Can you help me in booking my flight ticket from Mar 15th and Mar 17th?

ASSISTANT: Sure Cynthia Smith, I am happy to help you with that.

USER: Thank you.

ASSISTANT: Can I have your the airport codes of your journey locations?

USER: My trip airport codes will be DFW to LAX.

ASSISTANT: Ok, please let me know your preferable class.

USER: I prefer a business class.

ASSISTANT: Do you have any more specifications?

USER: I need a connecting flight.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Sorry Cynthia Smith, no flight is available to you in business class on your dates.

USER: Its ok, thank you.

ASSISTANT: Thank you for choosing us, have a good day.