You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Gregory Jackson.

ASSISTANT: Gregory Jackson, how can I assist you for the day?

USER: I want to change my existing reservation, can you please help me with that?

ASSISTANT: Sure, I will help you with that  cancellation. Please hold for a moment, let me check your previous reservation status.

USER: Sure, take your time.

ASSISTANT: Sorry to say that, there is no reservation found with your name in our database to cancel it.

USER: Ok, no problem. Thank you for your time.

ASSISTANT: You are welcome, thank you for contacting us. Have a great day.