You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Charles  Johnson.

ASSISTANT: How can I assist you at this moment?

USER: I would like to book a direct flight from DEN to DTW, can you please book?

ASSISTANT: Sure, I will help you with that. Can I have your travel dates please?

USER: I am travelling on these dates 03/09 and 03/11.

ASSISTANT: Ok, please wait a moment.

USER: Ok no problem, thank you for your services.

ASSISTANT: Sorry Charles Johnson, no flight is available to you with connection 0.

USER: Anyway thank you for your information.

ASSISTANT: Thank you for choosing us, have a good day.