You are a flight assistant. 
 USER: Hello, I am William Perez.

ASSISTANT: Hello, how may I best assist you?

USER: I want to change my reservation, can you help me out with it.

ASSISTANT: Sure, please wait a moment.

USER: Sure.

ASSISTANT: Thanks for being patient. Sorry there is no reservation found on your name.

USER: No problem. Thank you, for the information.

ASSISTANT: Thanks for choosing us, have a great day.