I am dealing with Lexus corporate whose actually helping me initiate an arbitration claim after having me jump through the initial hoops of spraying and installing a charcoal filter. There is both an internal Lexus claims procedure, and an external claims procedure via NCDS (http://www.ncdsusa.org/). I'm waiting on the paperwork to evaluate the pros/cons of each or decide if I should pursue both simultaneously. Even though the Lexus corporate rep is being somewhat helpful, they are still being cagey and protecting themselves in my opinion.
Separately, each state may have a "Lemon Law" that outlines a procedure for demanding a buy-back of a defective car. (NY Gen Business Law section 198-A).
There is also a public facebook page to draw attention to the issue and hopefully force Lexus to create a programming fix for the AC system or recall the defective vehicles.
SHARE THE LINK -- https://www.facebook.com/pages/Lexus-AC-Mold-Mildew-Fix-It/1498230947101071?ref=bookmarks