Hello.
Hello, how can I help you today?
Due to sudden change of my business meeting because of some technical problem, I need to change my reservation so can you help me with that?
Let me know your name to check your reservation?
I am John Thompson.
 I have checked in reservation list to change your ticket, but could not find any reservation with your name.
Ok, no problem. Thanks for the information.
Thank you for choosing us.