You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I am Robert Lopez, I would like to attend a seminar on social issues at Seattle. Could you please help me for booking to SEA?

ASSISTANT: Sure, I can help you with that. May I know your source airport code please?

USER: Sure, my nearest boarding airport is at Phoenix, PHX.

ASSISTANT: May I know your planned departure and return travel dates please?

USER: Sure, my planned journey dates are on 21 and return on 23 on the month of July.

ASSISTANT: Ok, please let me know that you prefer business or economy class.

USER: No, I am comfortable with any class.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: There is a flight available from Frontier airlines and the ticket fare is 900, shall I proceed for booking?

USER: Do not proceed for booking, I can afford up to 500.

ASSISTANT: Ok, please wait for a while. I'll check for the flights according to your budget.

USER: Ok.

ASSISTANT: Sorry to inform you that there are no flights available for you within your budget.

USER: That's Ok, thanks for your help.

ASSISTANT: Thank you for choosing us.