Patience.
Here is a letter from independent monitor David Kelley in reply to a complaint letter submitted by activist Prius owner Jessie Powell. Notably, he says he will "look into the issues [she has] raised."
With Jessie's permission, I am posting this to encourage others with complaints to submit them to Mr. Kelley. We may eventually see some results if enough of us write in with our experiences, providing all the evidence of whatever Toyota did or did not do in response to customer concerns and requests.
As Ovid opined, water dripping on a stone can eventually change the shape of the stone.
Mr. Kelley's email address for submissions:
toyotamonitor@cahill.com
(or he will accept postal mail too)