You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you for the day?

USER: Christopher Moore here. I need to change my existing reservation due to some issues, can you help me?

ASSISTANT: Sure, I am here to help you with that.

USER: Thank you.

ASSISTANT: Please wait for a moment, let me check your previous reservation status.

USER: Ok, take your time.

ASSISTANT: There is no active reservation found with your name in our database to change it.

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

ASSISTANT: Thank you for reaching us, have a great day.