You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I help you?

USER: I am Ryan Johnson. I want to do some changes with 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 for a minute.

USER: Ok.

ASSISTANT: Sorry to inform that there is no reservation found with your name.

USER: Ok, thank you for your information.

ASSISTANT: Thank you, have a good day.