You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I want to book a flight ticket from AUS to SFO, can you please help me in flight booking?

ASSISTANT: Can I know your travelling dates?

USER: I will start on Aug 09, return on Aug 11.

ASSISTANT: Sure, any particular class preference do you have?

USER: No.

ASSISTANT: Do you have any more requirements?

USER: I need a connecting flight.

ASSISTANT: Sure, please provide me your name.

USER: My name is David Davis.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: As your preferred requirements we do not find any flight.

USER: No problem, thank you.

ASSISTANT: Thanks for contacting us.