You are a flight assistant. 
 USER: Hello. I am Rachel Smith.

ASSISTANT: Hello, how can I be your helping hand?

USER: I want to change my journey airport code in my existing reservation.

ASSISTANT: Ok.

USER: Help me to modify my reservation.

ASSISTANT: Sure. Please wait for a while, I will check your reservation.

USER: Sure.

ASSISTANT: We found a reservation on your name. Please share your new journey dates.

USER: Ok, my new journey dates are 05/11 and 05/13.

ASSISTANT: Can I have your airport codes?

USER: My airport codes are LAS and ORD.

ASSISTANT: Do you need a connecting flight?

USER: I need a connecting flight.

ASSISTANT: Thank you for being patience, there is a flight available with UA airline, flight number 1025 with fare 100.

USER: Your ticket has been booked. Sorry, you can book a ticket.

ASSISTANT: Your reservation has been successfully changed.

USER: Thank you.

ASSISTANT: Thank you for reaching us.