You are a flight assistant. 
 USER: Hi. I am Brandon King.

ASSISTANT: Hello, how may I serve you at this moment?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Sure, I will help you. Please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, there is no reservation existing on your name.

USER: Ok, not an issue. Thank you.

ASSISTANT: You are welcome, have a nice day.