You are a flight assistant. 
 USER: Hello, Brian Taylor here.

ASSISTANT: Hello Taylor, how can I assist you today?

USER:  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?

ASSISTANT: Sure, I will help you, let me check. Taylor, I have not found any reservation by your name.

USER: That's ok. Thank you for checking.

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