Lexus Mark Levison sound system

Lexus owners should be aware that the Mark Levison sound system has a faulty amplifier that fails with very low usage. The problem has been known since this model was released and is very common and continues to this day. In my case the vehicle is out of warranty, but I find it unreasonable that having brought a Lexus whose list price was $179,000 that the radio failed under 24,000 km or equivalent to radio usage of less than half an hour a day, and to refuse any policy consideration on the $1250 replacement. This is very disappointing. I am also concerned that the brake pad wear sensors on the Lexus LS430 are only on the driver's side wheel i.e. RHS of the car. My brake pads caused some scraping noise at about 24,000 km on the pas senger side or kerb side. On inspection the pads were down to the metal, but there was no brake pad wear sensor on that side where they are most needed, hence no warning of imminent failure. It is common knowledge that the kerb side pads wear faster than the non-kerb side. The RHS still had 3 mm of lining, hence no warning. Pad wear sensors on the right-hand side of the car may be OK for a LHD vehicle, but are not much use on RHD vehicles. The ideal is brake pad sensors on all wheels. I was surp rised to find the brake pad wear being convinced that the warning lights would come on as indeed they have on one of my other vehicles with sensors on all four wheels. Again the front LHS was the first failing brake pad. I reported this to Lexus, who basically did not want to follow it up and without messing me about by having me present my car at dealership level. Having just been though this I declined. I'm not sure how to proceed next, but suspect this problem may be related to other makes of vehicles. Look forward to your advice.