They assigned one customer service specialist and one building products engineer for the six month test. These two people called every decision maker, influencer, and products user they could find in the 600 test companies. They did not try to sell. They did not offer discounts. They tried friendship and providing information.
People respond to friendship and relationship building.
But, they have to be the right people. If the experiment had been tried with the bottom customer quintile instead of the top, it probably would have not worked anywhere near as well. Because the bottom quintile probably make the bulk of their building product purchases elsewhere. They are loyal to some other firm, and bought from the test firm only items that their regular supplier does not carry. Some of them could have been turned around, certainly, but it would have been an uphill battle and not have had the same dramatic results.