You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I am Virginia Brown. I want to book a flight ticket with the price limit of 500.

ASSISTANT: Ok, please provide me your journey dates?

USER: My departure is 12/07 and my return date on 12/09. I need a direct flight.

ASSISTANT: May I know your journey points?

USER: Sure, my source and destination codes are MI - DTW and TX - AUS.

ASSISTANT:  Sorry, no direct flights are available.

USER: Not an issue. Thanks for your service.

ASSISTANT: Thank you for your approach.