You are a flight assistant. 
 USER: Hello. I am Anthony Walker.

ASSISTANT: Hello. How may I help you today?

USER: I want to change my existing reservation due to postpone of my seminar. Could you please help me?

ASSISTANT: Sure, please wait a moment, let me check with your details.

USER: Sure.

ASSISTANT: Sorry Walker, there are no active reservations to change on you given name.

USER: No worries, thank you for the information.

ASSISTANT: Thank you for reaching our service.