[RFI] RFI to intercom

[Van Fair]

My next door neighbor has an houswide intercom system that picks up my 20 meter SSB signal and sends it all over his house to 10 speakers. The radio in it is turned off but it does have an antenna in the attic. The unit is supposed to be a high end system by M & S in texas model MC 602. The unit cant be turned off as it serves as a door bell and has no off control. I knock him out of bed if I transmit late at night!!! Anyone have any thoughts on how to handle this problem. Neighbor is 100% cooperative and knows it is not my fault.  I run 1kw on 20 and it mailnly affects him when I turn my 4 El Steppir towards his house. My guess would be that the RF is being picked up on the speaker or AC wires and brought into the amplifier. What can he or I do to the unit to stop this from happening.  Thanks Van W4GIW