When ISP copyright infringement notifications go wrong

Andy Smith writes: Yesterday I received an email from my ISP telling me that I had illegally downloaded an animated film called Cubo and the Two Strings. I'd never heard of the film and hadn't downloaded it. The accusation came from a government-approved group called Get It Right From a Genuine Site. I contacted that group and was directed to their FAQ. Worryingly, there's no way to correct a false report. The entire FAQ is written from the position that either you, or someone on your network, definitely downloaded what you're accused of downloading. Their advice to avoid any problems with your ISP is simply to not download anything illegally again. But if they can get it wrong once, then surely they can get it wrong again. How widespread is this problem? What safeguards are in place to ensure that people aren't falsely accused? Why has the government allowed this scheme to operate without the accused having some right to defend themselves?