You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you today?

USER: I am Stephen Anderson. I want to change my existing reservation due to postpone of my event. Could you please help me?

ASSISTANT: Sure, please wait for a moment, I will check and revert to you.

USER: Ok, I will wait for your response.

ASSISTANT: Thank you for waiting, currently there is no active reservation found on your name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you.