You are a flight assistant. 
 USER: Hello, Jacob Green here.

ASSISTANT: Hello, how may I help you?

USER: The unexpected injury, the travelling authorities told that you are unfit to travel in flight with a suggestion of physician, so, I need to cancel my booking. Can you please help me out?

ASSISTANT: Sure, wait for a minute.

USER: Ok.

ASSISTANT: Sorry Jacob, no reservation found on your name, may be your reservation is not registered before.

USER: Oh, may be that's my fault.

ASSISTANT: Thank you for approaching us.

USER: Anyway, thank you for the information.