Hello,.
Hello, how may I address you now?
I already have an reservation to attend a meeting, due to some problems meeting place has been changed. So I need a few changes in my reservation. Can you please help me with that?
Sure, I would be happy to help you. May I know your good name please?
Edward Martin is my name.
Ok, please wait for a while, I will check the details and revert you.
Sure.
Sorry to inform you that there is no reservation found on you name.
Ok, not an issue. Thank you for your  information.
Thanks for reaching us and have a good day.