Hello.
user
Hello. How may I guide you today?
assistant
I want to change my existing reservation, can you please help me with this?
user
Sure, I am glad to help you with that.
assistant
Thank you.
user
Can I know your name to check your previous reservation?
assistant
I am Joseph Thomas.
user
Please be on  hold.
assistant
Sure.
user
We regret to inform you that, there is no reservation found on your name in our reservation list.
assistant
Ok, no problem. Thank you for your information.
user
Thank you for reaching us, have a great day.
assistant