I had this problem with both rear trims flying off. I tried to find them,,,, nope, can't do it, you have to buy a whole new window,,,,,,,,WHAT?????? says I. So I get on the computer and the telephone and finally contact Custome Service were I reached a nice you lady and told he the window trims both fell off and why can't I just get new trim parts rather than a whole new window. She checked on it and another person got back to me. This back and forth went on for a while and finally I brought up common sense,,,, DUH.
I reminded them that people who buy Lexus spend a lot on the name LEXUS, this brings comfort, dependability, QUALITY and customer satisfaction, of which this issue is not satisfying. I also reminded them I have a lot of friends with Lexus cars that will be interested to hear this. {The first friend I talked to about this had an RX and immediately started looking at other cars}. He wrote Lexus about that also. IN the meantime I kept after them.
Then one day I got an email from the LEXUS customer service that arrangements had been made at a local Dealer to replace my rear side windows FREE of charge. I set up an appointment, took the car out there, they replaced the windows, washed the car, AND filled up the tank with gas.
Moral is: They screwed up with a bad part and no easy way to fix it. Be strong, go after them and in time they most likely will fix it. And at the same time it is not a bad thing to threaten them with telling your friends and whoever else you can reach to stay away from Lexus. I am now a happy camper and enjoying the great ride of the RX.
The thing is, this is not a cheap fix and they will try to get out of it, stay with it, do not give up,,,,,,, and good luck
joro3743@gmail.com