You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am planning to book a ticket from LAX to HOU. Can you please help me out?

ASSISTANT: Sure, may I know your trip dates please?

USER: I am planning to travel on Nov 15 and return back on Nov 17.

ASSISTANT: Do you have any other requirements?

USER: My return time is evening and I am looking for a economy class.

ASSISTANT: Ok, can I know your name please.

USER: I am Scott Perez.

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

USER: That's fine, thank you for your service.

ASSISTANT: My pleasure.