Send them a note demanding that they forgo littering your yard with a mercury source.
I had a similar problem with the Minneapolis "Red" Star Tribune newspaper delivering unwanted free promotional papers to me.
They were nice when I talked to them and asked them to quit delivering papers to me, but the papers kept showing up now and again.
The only way I got their attention was to suggest that I might likewise deliver a "free" ton of manure to their front door. It's been a four years now without the "Red" Star newspaper on my doorstep.
You shoulda sued for illegal dumping of toxic waste in a residential zone.
:-P