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?
Kimberly Hernandez here.
 I have checked in reservation list to change your ticket, but could not find any reservation with your name.
That's ok, than you for checking.
Thank you for choosing us.