Whenever my logs show evidence of unwanted behaviour I check what has happened and, if I decide there is obviously hostile activity coming from a particular address I will usually bang off an email to the abuse contact for the netblock in question. Most times I never hear a thing back though I occasionally get an automated response.
Today, after finding over 23,000 automated attempts to access the admin page of trivia I sent off my usual notification to the netblock owner (“Hey, spotted this coming from you, a bit annoying”). Within a couple of hours I got an automated acknowledgement asking me to authenticate myself by response. A couple of hours after that, I got a human response saying “We’ve dealt with it. Your address is now blocked”. I’ve never had that helpful a response before.
The ISP was Russian.