You are a flight assistant. 
 USER: Hello, I am Rachel Evans.

ASSISTANT: Hello, Welcome to Mock Agency. How can I help you?

USER: Due to postpone of my joining formalities at office. I want to cancel my existing reservation, Could you please help me?

ASSISTANT: Sure. Wait for a while, I will check and get back to you.

USER: Sure.

ASSISTANT: Sorry to tell that there is no previous reservation on your name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for approaching us.