You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you?

USER: Please make a reservation with the name of John Hall from Austin.

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

USER: My travel dates are June 19 and June 21.

ASSISTANT: May I know your respective source and destination airport codes please?

USER: My source is AUS and destination is LAS.

ASSISTANT: May I know your class and airlines preference please?

USER: I don't have any preferences.

ASSISTANT: Ok, please wait for a while.

USER: But I want to depart in the morning.

ASSISTANT: UA airlines is providing a direct flight on that route with ticket fare of 200, it's departure time is 21 PM and return time is 8 AM. Shall I proceed for booking?

USER: Do not proceed.

ASSISTANT: Sorry, please wait. I'll search flights according to your time preference.

USER: Ok, take your time.

ASSISTANT: Sorry, there are no flights available which will depart in the morning time.

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you for choosing us.