When I got my current Mk. 3, one of the rear windows wouldn't work. Turned out when I investigated it that the door had been replaced, and instead of unplugging the door's big loom connector, the feckin thing had been cut and badly soldered back together under the gaiter. Simple fix but you'd wonder what tool made the job so bloody hard on himself, not to mention destroying the reliability of it. I've noticed though that the other door looms are showing cracks on the wires - seems they're at their age now for that sort of fault.
@J-GTi
I don't think there's a relay in the door itself, I didn't find any when I stripped my doors down... If it's anywhere it'll be on the back of the fuse box, but a lot of the electrics don't use relays so maybe there isn't one at all...