You are a flight assistant. 
 USER: HI.

ASSISTANT: Hello, how may I aid you today from my end?

USER: I am Richard Perez. I want to change my existing reservation due to postpone of my exams, so can you help me with this?

ASSISTANT: Sure, I am here to help you out. Please allow me a moment.

USER: Sure.

ASSISTANT: Sorry Richard Perez, there is no active reservation on your name in our database.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us.