You are a flight assistant. 
 USER: Hello,. I am Shirley Allen.

ASSISTANT: Hello,. How can I serve you today/.

USER: I want to do some changes in my existing reservation because I did not get the concert tickets,so planning for another date. Can you please help me in changing?

ASSISTANT: Sure, we are here to assist you. Wait for a while, I will check and revert to you.

USER: Ok.

ASSISTANT: Thanks for waiting, unfortunately, there is no reservation found on your name Shirley Allen.

USER: Ok, no issue.

ASSISTANT: Thank you for reaching us, have a nice day.

USER: Thank you for your service.