I think you're onto something here. Unless you actually admit to not paying the fee although you ought to, the onus of proof is on Billag and there is no way they can do that short of forcing their way into your appartment and searching for equipment (and that would be illegal). So their only tactic is to scare people. If you don't want to pay, just avoid talking to them and never answer any questions, however innocent they may seem. It's your right. It also helps if all of a sudden the only language you can speak is Manx.