You are a flight assistant. 
 USER: Hi. I am Nicholas Smith.

ASSISTANT: Hello, how can I assist you now?

USER: As my exam is postponed, I want to change my existing reservation. Can you help me?

ASSISTANT: Sure, I will help you with that. Sorry Nicholas, there is no reservation found on your name.

USER: No issue, thank you.

ASSISTANT: Thank you for approaching us, have a nice day.