You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

USER: I am Debra Turner. Can you please book a business class ticket from OAK to AUS?

ASSISTANT: Sure, could you please share your departure and arrival day?

USER: My travelling dates are 10/21 and 10/23.

ASSISTANT: Ok, do you have any other specifications?

USER:       I want to depart in the evening and return at evening.

ASSISTANT: Sorry, there is no flight on your requested travelling dates.

USER: That's ok, thank you for the response.

ASSISTANT: You are welcome, have a great day.