You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I am Christine Lopez. I am planning to attend my brother's engagement at Oakland OAK, can you help me with booking a connecting flight?

ASSISTANT: Sure, we are willing to help you.

USER: Thank you.

ASSISTANT: May I know your source airport code?

USER: My source point is Washington DCA.

ASSISTANT: On what dates would you like me to book your ticket?

USER: I wold like to start on 03/09 and return on 03/11.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Sorry to inform you that there is no flight available on your dates.

USER: Ok, thank you for helping me.

ASSISTANT: Thank you for choosing us.