Hello.
Hello, how may I be of your service?
As my exams were postponed, I need to change my existing reservation. Can you help me with that?
May I please know your name?
I am Anthony Parker.
Ok, I will help you. But, I am sorry to inform you that there is no existing reservation available on your name. Sorry for the inconvenience.
Thanks for assisting  me.
Thanks for opting us. Have a good day.