You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Can you please help me in booking my ticket from DFW to OAK?

ASSISTANT: Sure, please provide your trip dates.

USER: My trip dates are from 03/31 to 04/02.

ASSISTANT: Do have any other requirements?

USER: Yes, I need a single connecting flight.

ASSISTANT: May I know your name?

USER: Myself Helen Harris.

ASSISTANT: Sorry, we regret to inform you that there is no flight available as per your request.

USER: It's ok, thank you for your help.

ASSISTANT: Most welcome.