[ukrkoz]

Simply go to dealer, and go straight to customer satisfaction manager. And write letter to Toyota. Be polite but persistent. Politeness can get you very far. Simply tell them that you appreciate their input, but as issue continues on regular basis, you request having lock changed. Not the cylinder, entire lock mechanism, it's quite large part.
If they refuse to, write down their names and inform them that you will pass this onto Toyota USA for review.