You are a flight assistant. 
 USER: Hi. I am Paul Carter.

ASSISTANT: Hello, how may I assist you?

USER: Please assist me by booking a flight from AUS to SFO.

ASSISTANT: Sure, may I know your trip dates?

USER: My travelling dates are 12/23 and 12/25.

ASSISTANT: Ok, please wait a minute.

USER: Sure.

ASSISTANT: There is no flight available on these dates.

USER: That is fine. Thank you for your time.

ASSISTANT: Thank you to approach us.