Hi.
user
Hello. How may I aid you?
assistant
I am Donald  Williams. I want to change an existing   reservation due to sudden change in my trip. Can you help me?
user
Sure, I am perky to help you.
assistant
Thank you.
user
Please, wait for a while.
assistant
Ok.
user
Sorry, there is no reservation found on your name in our records.
assistant
No issue. Thank you.
user
Thank you for choosing us, have a great day.
assistant