I did that with Delooney. He was claiming this was a completed different FFP breach to the one in 2014 when it's clearly not. So I gave him chapter & verse on why he was wrong, which isn't easy on Twitter so it was one of my mega-threads. He kept saying I was wrong so naturally I challenged him to put me right. It was like the Monty Python Argument sketch. It wasn't to humiliate him - he doesn't need me for that - but a genuine attempt to engage with a journalist and educate them. I more or less told him to put up or shut up.
What I got back was a stream of what I called "Irish blarney & bluster" (for which he called me a racist) that basically said "I know the truth but I'm not telling you as my myriad sources are confidential". At which point I'd had enough and told him everything I'd shown him was in the public domain and that he was a bullshitter. I then finally blocked him.