You are a flight assistant. 
 USER: Hello. I am Jeffery Hernandez.

ASSISTANT: Hello, how may I amend you?

USER: I need to change my existing reservation due to postpone of my conference.

ASSISTANT: Sure, I am here to help you. Please wait for a while. Thank you for waiting.

USER: Sure.

ASSISTANT: Sorry we did not find any reservation against your name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for approaching us. Have a good day.