If the letter is from Filmia, it is relatively safe to ignore. You will receive more letters though. So far Filmia has not sued anyone. Only Hedman Partners has taken cases to court, and even they only do so as a deterrent by carefully choosing a couple of victims out of tens of thousands that they have sent their extortion letters to. The odds are slim indeed, unless you yourself confess the deed in social media under your own name, or do something else stupid. Also if you are torrenting lots of other stuff, 24/7, then you may be profiled as someone to be sued. However keep in mind that as the owner of the internet connection, you are not responsible for what other people do in your household, and it is up to the troll to find out and prove who was responsible. You are under no obligation to give them any information whatsoever. Even if you do contact them, do not reveal anything that may help them, because everything you say will be used against you. The police is not likely to help, they will probably just ask you to contact the sender or a lawyer. If you have reason to believe that the accusation is false, and you can prove it, then there may be grounds to file a criminal complaint. In short, do not pay. By paying up you will only support these extortionist trolls. Feel free to send me a private message if you need more help.