You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you at this moment?

USER: Due to some issues I have to cancel my flight ticket that one of my friend met with an accident, so please cancel my flight ticket booked on my name Samantha Mitchell.

ASSISTANT: Sure, I will help you about that.

USER: Thank you.

ASSISTANT: Sorry Mitchell, after checking in our database there is no active reservation under your name.

USER: Ok, I think it might be cancelled by my brother. Anyways, thank you for your search and information.

ASSISTANT: Ok, thank you for choosing our service.