G'day Greg,
Other than full soil fumigation (big bucks and kills
everything), I know of no other solution than glyphosate, and it takes many
repeat treatments. An initial spraying usually kills the main bulb, but then
the small side bulbs emerge. You just have to keep at it. Digging them out
is hopeless as you will just spread it further. In the days before glypho
the only realistic solution was to sell and move. Frankly I think you need a
solicitor, as the damage done will cost both money and hours of time,
devalue your property and ruin your enjoyment of your garden. Soil merchants
like this should be publicly exposed and dealt with by law. I'll bet you are
not the only customer with the problem, class action stuff.

What can I say, have a nice day?

China
Wingham
NSW