Seat heater failed (northern European model)

Just acquired a used 2007/8 Prius, and like all Sweden/Finland/etc models, it comes with the factory-installed cold-weather package (PTC air duct+radiator heaters, mirror heaters) seen in some other regions, but also with front seat heaters.

These were fitted to all Priuses sold in these countries, but do not appear in any of Toyota's own user or service manuals. So I can't find any info on where to look for fuses etc. I'm guessing they were fitted as they were imported.

This particular car has a failed driver seat heater - the switch itself does not glow when off or light up when on, as it should.

I'm assuming I should be starting by looking for its dedicated fuse, but there are no extra fuses visible in the standard fuse blocks, so maybe it's inline somewhere.

Before I start dismantling things and searching, does anyone have any other tips? Anyone worked on these heaters?

 

Ta for the suggestion. When I got around to testing it myself - turns out the heater is actually fine. It's only the switch bulb.