You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I want to do some changes in my existing reservation because my friends are not able to come on the those dates, can you please help me?

ASSISTANT: Sure, may I know your new airport codes please?

USER: I want to fly from OAK to JFK.

ASSISTANT: Please provide your travelling dates and name, for further proceeding.

USER: My trip dates are 10/18 and 10/20. Myself Michael Collins.

ASSISTANT: Thank you for providing your details, I found a flight with your details in UA airlines.

USER: You can book it.

ASSISTANT: Your ticket is booked with 1001 flight number.

USER: I appreciate your work, thanks for booking.

ASSISTANT: Welcome.