Cars still here, probably looking at a more suitable vehicle towards the autumn, but hopefully I can keep this too, seems a shame to let it go when it's been in the family since pretty much new.
Recently put a new set of Bosch Aero wipers on my E85 as the wiper blade on the drivers side was skipping at the top of the screen. With the new wipers it did the same, forgot all about it as the car doesn't get used much. Then it started happening again so I replaced the wiper thinking I'd reinstalled the old one instead of the new one. Still skipping. So I put on a new wiper arm, same issue. Cleaned the screen 1000 times with 4 different methods which improved it slightly. Clean out the wiper motor, to no avail. Then a brain wave accured(why this didn't happen sooner I'll never know)to swap the wipers around and the smaller passenger wiper on the drivers side worked fine.
So I've replaced with non-aero wipers (still Bosch) and the problem has totally disappeared. So just be weary if you're going to upgrade the Bosch Aero wipers as multiple sets had the same issue. I'm guessing due to the design they don't apply the appropriate pressure to the end of the blade.