You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I aid you?

USER: Sandra Clark is here. Aid me in booking a flight ticket to Dallas & Fort Worth, DFW under a price of 200.

ASSISTANT: Sure, I will help you. Please share me your trip dates?

USER: My trip dates are 05/30 and 06/01.

ASSISTANT: Help me with your source code?

USER: Austin, AUS is my source code.

ASSISTANT: Thanks for your details. Please wait.

USER: OK.

ASSISTANT: Thanks for waiting, I regret that there are no flights available by the specified price limit.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for choosing us, have a good day.