Just a helpful hinto fro anyone having to replace the rear wiper arm.
The new part from VW is £55 and the cap is £7.
I sourced a Febi branded one for £21. The model is Febi 177730. Direct replacement and includes cap. The wiper arm is of a decent quality and well made.
Handy hint - if you are having to replace the wiper arm due to the plastic cracking and the central ring spinning freely, remove the arm and leave the silver ring on the spindle. The ring is usually seized in place on the spindle. Save your effort trying to pull/lever it off - potentially causing damage. Just use a Dremel and cut a deep notch into the silver ring and then use a flat head screwdriver to leave the ring apart. It comes straight off the spindle.
Rich