That totally blows. I've been there myself. My suggestion would be to slice as much as you can, forehand and backhand. The lower you keep the ball on his end, the harder it will be for him to get under it for a lob/moonball.
Another thing you could do is moonball him right back. Play his game, it will suck but you might frustrate him just as much as he frustrates you.
If you get a lot of these types of players at your level, then you should play up, 4.5's. You'll likely get more competition and less moonballers.
Bullfan, "Bull rap, there is video evidence." and "Dude it's on the Internet, and hasn't been hidden."