Hi, I am Stephanie Carter.
Hello. How can I help you today?
Owing an emergence, I want to change my existing reservation. Can you please help me with it?
 I understand your request, I'll help you with this. Please wait a moment I will check the reservation list.
Ok.
I have checked in reservation list to change your ticket, but could not find any reservation with your name.
No problem, thanks for the information.
Thank you for availing us.