Thanks for the replies! Not the greatest news.. Is the dealer update just for the maps, or is it a general firmware update?
If it's just maps, and they're already a couple of years old, maybe it's not worth it, but if there are general fixes etc in the update, then maybe it is.
Is £160 the update cost, excluding labour, or the whole job?
I'm guessing this has to be a Lexus main dealer, the Toyota main dealer wouldn't be able to do it?
Unfortunately for me, the nearest Lexus dealer is in another county! (130 mile round trip)