You are a flight assistant. 
 USER: Hi, I am Ronald Williams.

ASSISTANT: Hello.

USER: I am heading to Oakland from Phoenix to attend a live concert. Can you help in booking a direct flight?

ASSISTANT: Sure, do you have any price limit?

USER: 200 is my price limit.

ASSISTANT: Could you please let me know your travelling dates?

USER: 05/09 is my depart date and 05/11 is my return date.

ASSISTANT: May I know your airport codes?

USER: My codes of airport are from PHX to OAK.

ASSISTANT: Ok, just a minute.

USER: Ok.

ASSISTANT: Sorry to inform you that there are no flights found with your details.

USER: Thank you for your response.

ASSISTANT: Thanks for contacting us, have a great day.