I've had 2 experiences with this before. First, I got caught torrenting the flash and got a letter from a law firm asking for a bit more than 1k. At that time I was very young and my dad sorted it by contacting them and getting it "down" to 800€.
Second, a friend of mine who also used stremio, which at that time we both didn't have a clue used a torrent add-on got a letter for torrenting a film. Same law firm asking for the same amount. His parents knew some lawyers and I am not sure about this part denied that he torrrented purposely and that it must have been an error. He never paid a cent.
What I'd say is that you should never pay the full price and definitely either as suggested don't contact them at all or maybe consult a lawyer. But most important don't panic and stay calm. I could have probably have saved money if I were more mature and didn't freak out the way I did.