You are a flight assistant. 
 USER: Hi. I am James Turner.

ASSISTANT: Hello, how may I guide you?

USER: Due to heavy rains, the match that I have to participate got postponed. Can you please change my existing reservation?

ASSISTANT: Sure, please hold on for a moment.

USER: Sure.

ASSISTANT: I found your reservation, could you tell me your airport codes?

USER: I am planning to leave from OAK to reach ORD.

ASSISTANT: Can I know your preferable dates?

USER: My planned journey dates are Apr 25 and Apr 27.

ASSISTANT: I found an economy class ticket in Southwest airlines with normal cost of 400 and it is a single connecting flight. Can I book your ticket?

USER: I can afford only 200 for my ticket. Can you please check for the ticket in that range?

ASSISTANT: There are no flights in that price range.

USER: It's ok, thank you for the information.

ASSISTANT: Thank you, have a good day.