Hi.
Hello, how may I oblige you today?
Due to sudden change in my trip to another location, I would like to do some changes in existing my reservation. Can you please help me out?
Sure, may I know your good name?
Catherine Baker.
Ok, please wait for  a while.
Sure.
I have checked in reservation list to change your ticket, but could not find any reservation with your name.
That's ok, thank you for checking.
Thank you for opting us.