Hi, I am Donna Lee.
Hello, how can I aid you?
  I already have an reservation to attend at my meeting, due to some problems meeting place has been changed. So I need a few changes in my reservation. Can you help me with changing reservation?
Sure, I am willing to help you. Please stand by I will get back to you.
Ok.
Thanks for your time, sorry to say no reservation found with your name.
OK, no issues.
Thank you for reaching us, have a nice day.