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 IAH to ORD?

ASSISTANT: Sure, may I know your trip dates?

USER: My trip dates are from 12/15 to 12/17.

ASSISTANT: Do you have any other requirements?

USER: Yes, I need a single connecting flight.

ASSISTANT: Ok, may I know your name?

USER: Myself Andrew Lopez.

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.