Hello. I am Joshua Green.
user
Hello, how may I help you? Nice to meet you  Joshua Green.
assistant
My exams have postponed suddenly, so I want to change my existing reservation. Can you help me with this?
user
Ok, let me check once. I can help you. Sorry  Joshua Green, there is no reservation found with your name to change.
assistant
No problem. Thank you for your time.
user
You are welcome.
assistant