You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you now?

USER: My name is William Taylor. I want to change my existing reservation due to postpone of my conference.

ASSISTANT: Sure, we are here to help you. Please wait for a minute.

USER: Sure.

ASSISTANT: Thank you for waiting, there is no reservation found on given name.

USER: Not an issue, thanks for your service.

ASSISTANT: Thank you for reaching us.