Unfortunately I also have an 'troublesome' (!) neighbour who complains to the local authorities about the noise.
Buy a gun and shoot whoever stops you playing.
Or, one of my favorite tools, use a marine air horn, and, by amplifying sounds from her place, blast it each time she, say, opens a cupboard or turns on a faucet.
Damn... Sorry to hear that. I had that at one stage when I was only on an upright (I was practicing Petrushka 7 hours a day though )When I moved into my new home, had acoustic panelling to absorb the sound inside, and double glazed windows to stop the noise from leaking outside. I played some Chopin Ballades at 11pm at night, and my neighbours were none the wiser. Definitely worth looking into as it really provides a fantastic room to practice the piano in all it's glory... without annoying some cranky bugger next door.