You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,how may I assist you?

USER: My name is Virginia Collins, I want to book a direct flight from Houston to attend a meeting. Can you book a flight with in fare of 500?

ASSISTANT: Sure, I am here to help you. May I know your trip dates?

USER: I will fly on 09/03 and return on 09/05.

ASSISTANT: Where you need to catch the flight and land?

USER: My source airport code is TX-HOU and my destination is TX-DFW.

ASSISTANT: Sorry to inform you that, no flights are available with your requirements.

USER: Ok, thank you for the information.

ASSISTANT: Thank you for availing us.