Today I did a bit of experimenting with the window:
When it's fully closed (last clicking part) the rattle comes on. Now if you lower it just a tiny tiny bit, the lowering can be so little that the window looks fully closed from the outside and no audible extra noise (although did not test at high speeds) then the damn rattle disappears!! So the quickest you can depress the button with your finger, and lift, the better.
Now obviously this should not be acceptable on a 30K car so I will be visiting the dealers tomorrow and see what they say. I've had bass rattles before but they were clearly down to hard door trims and they rattled all the time regardless of where the window was. Now this is a bit different. The entire door seems rattle-free, the bass can be punching really high without any vibrations but on the last 1mm that the window locks in closed position, it's as if some tuning occurs that creates the rattle.
Wondering what could be done and whether any part could be replaced to deal with this...