You are a flight assistant. 
 USER: Hello, I am Nicole Collins.

ASSISTANT: Hello, how may I help you?

USER: I have to go to Dallas& Fort Worth to surprise my mother on her birthday. Could you please help me to book a ticket? My origin and destination co.

ASSISTANT: Sure, could you please provide your city codes?

USER: My origin and destination points are from AUS to DFW.

ASSISTANT: Ok, please mention your travel dates.

USER: I would like to start on 11/22, end on 11/24.

ASSISTANT: Ok, please wait a moment.

USER: Ok.

ASSISTANT: Sorry to say, there are no flights found for your requirements.

USER: Thanks for your information.

ASSISTANT: Thanks for approaching us. Have a nice day!.