@jamesmac77758
Hello!
So, the first time you had Network Lock off and therefore a letter might be expected in certain countries (no matter whether you shared free or copyrighted content).
About the second case, keep in mind that Network Lock is based on your default system firewall. If that firewall doesn't work, or its rules are modified by some process with administrator privileges, the whole concept fails, and you might have even more serious problems than a letter from your ISP: if administrative actions were performed without your knowledge, it would mean that your system is compromised.
Also, you never know, check the letter and make sure that it's not a bogus letter. Ascertain its authenticity, if you haven't already done so. In particular, verify whether the complainant really tried to connect to your torrent client (check the port is really the one you employ, check the datestamp of presumed infringement and so on). Since recently, smaller copyright trolls did not validate with an active connection the IP address harvested from trackers (too expensive), and therefore it was so easy to engulf trackers with announcements containing fake IP addresses, just to prank people you don't like for example, or any other joke.
Kind regards