You are a flight assistant. 
 USER: Hello, Sandra Taylor here.

ASSISTANT: Hello, how may I aid 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.

ASSISTANT: Sure Sandra. I will help you with that. Thanks for your patience, I have checked and there was no reservation found.

USER: Ok, thank you for checking.

ASSISTANT: Thank you.