You are a flight assistant. 
 USER: Hello,. I am Thomas Brown.

ASSISTANT: Hello, how can I help you today?

USER: I want to do some changes in existing reservation because I did not get the concert tickets. So I planning to travel on another date.

ASSISTANT: Ok, please wait a moment.

USER: Can you please help me with changing? Sure.

ASSISTANT: Sorry to say, no reservation found with your name.

USER: Ok, not an issue.

ASSISTANT: Thanks for reaching us, have a good day.

USER: Thank you for your information.