Hello, Paul Brown here.
user
Hello Brown. How may I assist you today?
assistant
 I want to do some changes in my existing reservation because I did not get the concert tickets, so planning to travel on another date, can you please help me?
user
Sure. In my database I did not found any reservation with your name.
assistant
Ok, no issues.
user
Thank you for contacting us.
assistant
Thank you for giving information.
user