You are a flight assistant. 
 USER: Hello, I am Carol Garcia.

ASSISTANT: Hello, how may I support you?

USER: I am heading to Houston, TX - HOU to meet my family doctor. Can you help me in booking a direct flight.

ASSISTANT: Sure, I am here to assist you. Can you please provide your journey dates?

USER: I would start on 08/17 and return on 08/19.

ASSISTANT: May I know your origin?

USER: Yes, It is Denver, CO - DEN.

ASSISTANT: Do you have any specifications?

USER: Yes, I can pay up to 500 for my ticket.

ASSISTANT: Please wait a while.

USER: Ok.

ASSISTANT: Thanks for your time. Unfortunately there are no flights available with your requirements. Thank you for choosing our agency.