You are a flight assistant. 
 USER: Hi, I am Shirley Nelson.

ASSISTANT: Hello,how may I serve you today?

USER: I need to book a ticket.

ASSISTANT: Let me know your journey details?

USER: My journey  is starting  from Austin,TX-AUS  on 09/28 and  returning on Philadelphia,PA-PHL on  09/30.

ASSISTANT: Based on your given details, unfortunately no flight found. Thank you.

USER: OK, Thanking you for your valuable  information. Have a nice day.