You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: My budget limit is 500 so can please check is there any flight available with this price limit to Oakland?

ASSISTANT: Sure, can I know your travel dates?

USER: My departure date is 06/06 and also confirm my return ticket too on 06/08.

ASSISTANT: Please share your airport codes.

USER: I want to fly from DCA and destination airport is OAK.

ASSISTANT: Can I know your name?

USER: Sure, my name is Michael Williams.

ASSISTANT: Sorry Williams, there is no flight available on your requested dates.

USER: Oh! It's ok no problem, I will go with another airline. Thank you for your service.

ASSISTANT: Thank you.