You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: Please book a flight ticket on dates Sept 11 and Sept 13.

ASSISTANT: Sure, I can help you.

USER: Thank you.

ASSISTANT: Please share me your airport codes.

USER: My airport codes are ORD and DEN.

ASSISTANT: Do you need any break?

USER: Yes, I need a connecting flight.

ASSISTANT: Is there any other  specification?

USER: I need a ticket in business class.

ASSISTANT: May I know your name?

USER: My name is Richard Roberts.

ASSISTANT:  We are unable to provide flight in between your journey routes due to some technical up-gradation at destination airport.

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

ASSISTANT: Thank you for reaching us.