Hello.
user
Hello. How may I help you?
assistant
I want to change my existing  reservation. Can you help me?
user
Sure, I help with that.
assistant
Thank you.
user
May I know your name please?
assistant
Sure, I am Sarah Collins.
user
Ok, wait for a while.
assistant
Sure.
user
Sorry for inconvenience there are no reservation found on your name.
assistant
Ok, no problem. Thank you for your information.
user
Thank you for approaching us.
assistant