Ok, I don't know what you've done in the past, but...would you be willing to force his hand? Like, not provoke him so much as very blatantly tell him that he's pissing you off and making you uncomfortable and that he needs to stop or you're going to pursue official channels? Because after that - even if you're bluffing in the beginning - if he keeps going on or steps everything up, you could probably work the harassment angle.