I'm having similar prob's with my abs system. According to vcds, i had the R/R sensor go up the swanny with the F/L sensor, so replaced them and cleared all fault codes. and still the abs light is shining brightly! So had a chat with my local VW dealer, i knew more than the technician! lol. Alas, they want £75 to look at my car, I said no thank's.., I'll go buy the full license through Ross-Tech then you can do all coding of modules like the problem you've come up with. Persevere and you'll get to the bottom of it