Well, alright. So, you couldn't do anything then. Maybe you were tied up or something. I'll give you the benefit of the doubt. Why not square off with him now. Go toe to toe with him about it. He'll either back down out of fear and you win or he won't and then it's on. I like the people I'm paying back to know it's me. They tend not to fuck with me again. And if they do, I just get worse.
As for messing with his car, I prefer the "Drive him insane" approach.
Cars now have a regulator in the gas tank so only the nossle from unleaded fuel pumps can be put into them. This is easily removed with a hammer and screw driver. Then drop a baked plastic ping pong ball into the gas tank.
When the car starts, it runs for a little while until the suction from the fuel line pulls the ping pong ball down to the fuel line. Then the car stalls. After the stall, the suction is gone and the ball floats back to the top of the gas. The car starts and everything repeats. No real damage other than the regulator so not a whole lot of legal risk but he'll spend ALOT of money and time trying to figure that one out.
The ping pong ball has to be baked plastic though or the gas will eat right through it.
