Horn and Alarm Malfunction

[cris810]

Horn and Alarm go off when locking car, or at will when car is parked. Have had 4 repairs done by dealer. Get more phone calls from Mercedes Response Team than from friends! Dealer found water inside siren horn........pins rusted, among other things. Is this common? Should source of water be fixed? Where is it coming from? Have you heard of other incidents of this occurring? Please advise.