You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am James Lee.

ASSISTANT: How can I help you today?

USER: I want to book a flight ticket from OAK to DTW. Can you help me?

ASSISTANT: Sure, we are here to help you in booking. On which dates would you like me to book a flight ticket for you?

USER: Thank you. 12/15 and 12/17 are my travelling dates.

ASSISTANT: May I know if you prefer to have any other comforts in your journey?

USER: I need a direct flight.

ASSISTANT: Can I know your depart and arrival timings?

USER: I need to depart in the afternoon and my return time should be afternoon.

ASSISTANT: Ok, please wait a moment.

USER: Ok.

ASSISTANT: Thank you for waiting, we are unable to provide flight in between your journey routes due to some technical up-gradation at destination airport.

USER: No issue. Thank  you.

ASSISTANT: Thank you for approaching us.