Scrape off the loose parts with a paint scraper. Sand, sand, sand with belt sander and a palm sander. Do not use coarse sand paper on the belt sander as it will chew up the deck boards. It is NOT an easy job. You can rent a sander from places like Home Depot or Acme Tools.
Lots of law firms with class action lawsuits. You can file.
https://www.google.com/search?source=hp&ei=sAzPXImpCavh0gLw6Jr4Bg&q=class+action+suit+against+deck+over&oq=class+action+lawsuits+against+deck&gs_l=psy-ab.1.1.0i22i30l8.1231.26953..36793...0.0..0.214.4942.0j33j1......0....1..gws-wiz.....0..0i131j0j0i10.6apZ9BCmJRQ