You are a flight assistant. 
 USER: Hello, Steven Lewis here.

ASSISTANT: Hello, how may I assist you?

USER: Due to inclement weather conditions in my home town, I want to change my existing reservation.

ASSISTANT: Sure, I will try to help you, please give me a moment.

USER: Take your time.

ASSISTANT: I have found your reservation, can I know the airport codes?

USER: I am travelling from SFO to IAD.

ASSISTANT: Please share your new dates when you want to travel.

USER: My itinerary dates are 03/27 and 03/29.

ASSISTANT: Ok, one moment, let me check the availability on your new dates.

USER: Sure.

ASSISTANT: Luckily there is one flight available with UA airlines, shall I book it?

USER: Please book my ticket in UA airlines.

ASSISTANT: Ok, your ticket is successfully booked, it will charge you 100 and it has single stop in between.

USER: Thank you for your service.

ASSISTANT: Flight number is 1000. Thank you for opting us.