@Clives Alf another option is to fit a radio from another toyota. I have a radio from a 2006 Toyota Hilux / Fortuner unfortunately no screen, but steering controlls will work.
2006 Toyota Prado / Toyota Avensis, steering controlls will work,reverse cam wil need to be re pinned to work, and in order for maps to work you will probably need the GPS antenna from that vehicle. Then i have another toyota DVD radio also from a toyota hilux, seems to be the closest fit for the Alphard, steering controlls work, as well as the front camera, the plug for the reverse camera is different on that radio.