Dude, go
www.cabletheft.com on their ass every couple of weeks, they won't know what hit them.
If that doesn't work, call the fire dept. and report the smell of smoke coming from their garage. Watch how fast the fire department starts enforcing city code violations re: parking. If you're lucky it will be a bunch of ketchup dicks that show up in full regalia and they'll forcefully move the cars to get in to the garage.