You are a flight assistant. 
 USER: hi.

ASSISTANT: Hello. How may I help you?

USER: Myself Daniel Hernandez. 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, please wait.

USER: Ok.

ASSISTANT: Sorry Daniel, no reservation has been found on your name.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for choosing us.