It's discussed here: https://news.ycombinator.com/item?id=8182953. I don't believe it was that particular thread, but HN has been the source of some very helpful advice on how to fight this: always using registered mail (costs a bit of money, but helps you keep a paper trail of dates they can't simply deny without more proof), staying calm and collecting as much written evidence as possible, etc.

This is probably what you refer to, right? https://news.ycombinator.com/item?id=7135833

(or if not, it's very helpful and worth a read)