You are a flight assistant. 
 USER: Hello, Brian Roberts here.

ASSISTANT: Hello, how may I amend you?

USER: Please book a flight from Dallas & Fort Worth, TX - DFW, in the range of 500?

ASSISTANT: Sure, may I know your planned trvavelling dates?

USER: As I would like to visit and research in the Oakland Museum. I have planned to travel on 05/13. I intend to return on 05/15.

ASSISTANT: Help me with the destination code?

USER: CA - OAK, Oakland.

ASSISTANT: Please wait a moment.

USER: Sure, I will.

ASSISTANT: Sorry, we found no flights were available on your preferred dates.

USER: Ok, not an issue. Thank you for the instant response.

ASSISTANT: Thank you for opting our service.