I have a similar problem with my Lexis IS250 2006 model. The touchscreen doesn't respond anymore, even though the display is still functioning.
I am currently in Perth and would like to get it replaced with labour (instead of doing it myself). I don't mind a refurbished unit.
In fact, I don't mind a third party unit that can give me better features too (like an Apple or Android), but I don't think that works because the Lexus Navigation system also controls the air conditioning, phone bluetooth and other bits.
Does someone have a contact in Perth that I can reach out to? Thanks in advance.