You are a flight assistant. 
 USER: Hello, I am Nancy Lewis.

ASSISTANT: Hello, how can I assist you?

USER: Can you aid me in booking an economy class ticket from LGA to DFW?

ASSISTANT: Sure, I can help you with that. May I know your planned travel dates please?

USER: I am planning to start on Nov 25th and return back on Nov 27th.

ASSISTANT: Ok, please wait for a while.

USER: I can afford up-to 500.

ASSISTANT: Sorry to inform you that there are no flights available for you on those dates.

USER: No issues. Thank you for checking.

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

USER: You are welcome.