Hello.
user
Hello. How can I assist you today?
assistant
I am Edward Evans. I am planning to change an existing reservation, can you help me out to change reservation?
user
I will help you Evans, let me check.
assistant
That's fine, take your own time.
user
Sorry Evans, I have not found any reservation under your name in our database.
assistant
That's really sad to hear. Thank you for  your help.
user
Thank you for contacting us, have a nice day.
assistant