You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I am Samuel Miller. I want to change an existing reservation, due to health issue. Can you please change my reservation?

ASSISTANT: Ok, give me a moment.

USER: Sure. Take your own time.

ASSISTANT: Sorry to inform you that there is no reservation found on your name in our database.

USER: That's fine. Thank you for your service.

ASSISTANT: Thank you for reaching us.