Hi. I am Joshua Evans.
user
Hello, how may I assist you at this moment?
assistant
I want to change an existing reservation due to sudden change in my trip. Can you help me?
user
Sure, we can  help you.
assistant
Thank you.
user
Please wait for a while.
assistant
Ok.
user
Sorry to inform you that, we couldn't find any reservation with your name in our database.
assistant
No issue. Thank you.
user
Thank you for choosing us.
assistant