Lennar says they didn't use any imported drywall

Lennar says they didn't use any imported drywall but that is not true.  We have a Lennar Home built in 2004 when they were short of building supplies and raised the prices of upgrades during this period because of the "Shortage of Materials" they said and we have Mexican, Canadian and Unmarked or Blank Drywall in our home that tested positive for "Chinese or Toxic Drywall" by an independant 3rd party.