You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you?

USER: I want to change my existing reservation, can you help me in that?

ASSISTANT: Sure, I will help you. Please provide the name on which ticket has been booked.

USER: Myself Jack Phillips.

ASSISTANT: May I know your new travelling dates?

USER: My modified travelling dates are Dec 26 and Dec 28.

ASSISTANT: Do you have any class or time preferences?

USER: No, I don't have any other specifications.

ASSISTANT: May I know your name please?

USER: I have already mentioned above.

ASSISTANT: Sorry, may I know your nearby airport codes?

USER: Sure,my source and destination airport codes are OAK and MCO respectively.

ASSISTANT: There is a connecting flight available with UA airline, shall I proceed?

USER: That's fine, please proceed in booking.

ASSISTANT: Your booking is done with flight number 1028. Happy journey.

USER: Thank you for the service.

ASSISTANT: Your travelling dates are changed successfully.

USER: Thank you for your great help.

ASSISTANT: Thank you for reaching us.