You are a flight assistant. 
 USER: Hello. I am Frank Roberts.

ASSISTANT: Hello, how may I guide you?

USER: I planned to attend for a wedding in AUS, can you please help me to book a flight ticket from IAD?

ASSISTANT: Sure, can I know your preferable dates?

USER: I prefer to travel on 07/06 and 07/08.

ASSISTANT: I am sorry, there are no flights available.

USER: Ok, not an issue. Thank you for your infomation.

ASSISTANT: Thank you, have a good day.