You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: William Campbell here.

ASSISTANT: How may I guide you today?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Please wait a moment to check your previous reservation.

USER: Ok.

ASSISTANT: I have found your reservation. Can you please provide your new journey airport codes for booking?

USER: My airport codes are LAS - ORD.

ASSISTANT: Ok, may I know your planned dates of travelling?

USER: My trip dates are 06/04 - 06/06.

ASSISTANT: Do you have any specifications?

USER: I need an economy class with a single connection.

ASSISTANT: Wait a moment please.

USER: Ok.

ASSISTANT: I have found a direct flight in your journey having with the fare of 100 provided by AA airlines is matches with your requirements. Are you comfortable with this flight?

USER: Please reserve.

ASSISTANT: Ok, your ticket has been confirmed in flight number 1028.

USER: Thank you.

ASSISTANT: Thank you for reaching to our services, hope you have a great journey.