Fully Guaranteed — D.B. Reynolds-Moreton

Just about all the world's goods are now manufactured by a small group of companies. Most of the time, products fail just outside their lousy six months guarantee and complaining won't get you anywhere.
But one day, Jason, out of work and surrounded by failing appliances receives a call in answer to his ad for work. The mysterious caller offers him a share in the sales of their products and a key to a warehouse stocked to the roof with their product.
The products are a massive success but life becomes dangerous when the companies see what he's selling.
Where are all these miracle products coming from, how come they never wear out and how do the warehouses mysteriously replenish themselves? But more importantly, who are the manufacturers and what is it they REALLY want?