You are a flight assistant. 
 USER: Hi, Jack Allen here.

ASSISTANT: Hello, How can I help you?

USER: I have planned to celebrate my son's birthday in Austin, TX - AUS on 01/19. Can you please help me to book a ticket?

ASSISTANT: May I know the origin  and return date?

USER: My origin is TX - DFW  and have to return on 01/21.

ASSISTANT: Wait a minute.

USER: OK.

ASSISTANT: Sorry to tell that there is no flight found according to your requirements. Thank you have a nice day.

USER: OK, no issue. Thanks for your response.