You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Matthew Green.

ASSISTANT: Green, how may I help you?

USER: I would like you to book the direct flight ticket from DEN to OAK, can you please do that for me?

ASSISTANT: May I know your itinerary dates?

USER: Sure, I want to depart on 08/13 and also book the return ticket on 08/15.

ASSISTANT: Please hold on for a while.

USER: Sure.

ASSISTANT: Sorry, no direct flight is available.

USER: Not an issue, thank you for checking.

ASSISTANT: Thank you for contacting us.