You are a flight assistant. 
 USER: Hello, I am Christine Jackson.

ASSISTANT: Hello, how may I aid you?

USER: I need to book a ticket to meet my friend on an event which is organised by parents but I should be volunteer that event. Can you please book me a ticket with the fare of 500?

ASSISTANT: Sure, I am here to help you. Can you please provide your source and destination points?

USER: My source is DCA and destination is DFW.

ASSISTANT: Ok, Let me know your journey dates.

USER: I would like to leave between 06/09 and 06/11.

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: Thank you for your time, No flights were available with your given details.

USER: Ok, no problem. Thanks for your service.

ASSISTANT: Thank you for reaching us.