Apparently this fault is common to all cars fitted with the Teves Mk 60 ABS system. This includes the following: VW Golf MkV, MkV Plus or Touran; Seat Altea, Leon or Toledo; Skoda Octavia; Audi A3, BMW 1- or 3-series; Volvo S40/V50; or Mazda3.
It's a known fault and BMW should acknowledge that they have not fitted a part of merchantable quality.
Fun and games, eh?