Hello. Jack Walker here.
user
Hello Jack. How can I help you today?
assistant
I want to make 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, I will help you Jack. Please give me a moment.
assistant
Ok.
user
No previous reservation available in our data on your name  Jack Walker.
assistant
It's ok, no problem. Thank you for checking.
user
Thank you for reaching us, have a nice day.
assistant