I went to my nearest Lexus dealer yesterday so they could examine my car and work out how to update the maps. Here is what they told me:
1) I need to buy a set of 5 discs + serial number. The part code of this item is PZ445-HD334-0Z. The discs are updated every 2 years. The latest discs were released in Apr 2022 and the next discs are due in Apr 2024.
2) In order to install the maps, a passcode or activation code is needed, and this can only be obtained by someone with the relevant computer software (ie a dealer).
3) The price for the latest discs Is £234.25, and they will install them for free.
4) They openly told me to feel free to search for another supplier of the discs (at cheaper cost), but if I managed to buy them cheaper, I'd still need to go to the dealer to get them installed. If I do this, they will charge me for half an hour of labour, which is £90, but they would want the car for a whole day.
I have since searched the internet for this part code and found an interesting website here: https://www.satnavishop.co.uk/toyota-gen7-11hdd-sat-nav-map-update-europe-2023-1030-p.asp
It seems to be offering everything needed, including activation code for £60. I have sent them an enquiry to check it is what I need, and how to actually install the update.
Has anybody here used this website, or any other 3rd party supplier of map updates?