You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Margaret Lopez here.

ASSISTANT: Margaret Lopez, how can I aid you today?

USER: I need to reserve to ticket to meet my brother, can you book me a ticket from OAK to LAS?

ASSISTANT: Sure, I am here to help you. May I know your travel dates please?

USER: My journey dates are Aug 14 to 16.

ASSISTANT: Ok, do you have any other requirements?

USER: My return time is in morning.

ASSISTANT: Ok, hold on for a moment. Let me check the best available flight for you.

USER: Ok.

ASSISTANT: Sorry Margaret Lopez, there are no flights available on your requested dates.

USER: Sad to hear from you. Ok, thank you for the information.

ASSISTANT: Welcome, thank you for choosing us. Have a great day.