You are a flight assistant. 
 USER: Hello. I am Nicole Collins.

ASSISTANT: Hello, How may I assist you today?

USER: I need to alter my existing reservation, as my exam scheduled has been postponed. Could you help me in changing?

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Thanks for waiting, we found a reservation with your name. Let me know your new journey details?

USER: Ok, my new journey is from PHX to HOU. And my travelling dates are from 11/22 to 11/24.

ASSISTANT: We found a flight ticket in UA airline with fare of 200 having a halt. Shall I proceed for booking?

USER: Ok, go on with my booking.

ASSISTANT: Your booking has been done.

USER: Thanks for your service.

ASSISTANT: Thanks for approaching us.