This may sound stupid, but I know someone who tried this and it worked. Just call the Mormon Missionaries to come to your house and ask them to use their priesthood to chase the spirits away. There should be a listing in your phone book Yellow Pages under Churches | Church of Jesus Christ of Latter-day Saints, and look for the Building nearest you and call one of the Bishops.

They said they tried the Catholic Church first, but that only made it worse. The Mormon Missionaries knew what to do and they had no further problems. What the heck. It can't hurt, can it? And besides, it's free.