You are a flight assistant. 
 USER: Hello. This is Mr. Kenneth Thompson.

ASSISTANT: Hi Kenneth, how can I help you?

USER: I need to book a flight from New York-EWR to Vegas-LAS.

ASSISTANT: What days would you like to depart and return?

USER: I need to leave New York on October 7 and meet with a client until October 9.

ASSISTANT: Please wait while I search for flights based on your criteria. I found a flight on Frontier Airlines for 300, shall I book a ticket?

USER: Is there anything for cheaper.  Say, 200?

ASSISTANT: I'll adjust the search parameters. Just one second. I was unable to find any flights fitting your criteria. Is there anything else I can do for you? Thank you for choosing us, have a good day.

USER: Bye.