You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

USER: Can you please book a direct flight ticket to San Francisco on 07/28?

ASSISTANT: Sure, I will help you with that.

USER: Thanks.

ASSISTANT: Can you please mention your airport code names?

USER: I want to fly from LAS and destination airport is SFO.

ASSISTANT: Do you need any help from us for booking return flight ticket?

USER: Yes, please book my return ticket also on 07/30.

ASSISTANT: Please hold on a moment, I will check flight availability in this route.

USER: Ok.

ASSISTANT: Sorry no flights available in this route as per your requested dates.

USER: Oh! It's ok no problem, I will go with another airline service. Thank you for your service.

ASSISTANT: You are welcome. May I know your name for documentation purpose?

USER: Sure, my name is Emma Brown.

ASSISTANT: Thank you for your information.