im in pretty much the same situation as you
revo 2+ and stage 2 dsg software - my dsg box has been lurchy in 1st and reverse for the past 6 months, car is 2 years old and 35k miles
took it to stealers last november and they confirmed mech unit is knackered
unfortunately they will not replace it under warranty due to my modifications...
i complained to vw hq and they also confirmed they would not do it under warranty.
replacement mech unit is c£1100 + fitting

if your dealer is nice then they might do it under warranty or offer to split the cost - unfortunately dovercourt battersea (avoid like the plague) would do neither!
stevep had his mech unit replaced first time under warranty but i believe it went again after less than 10k miles - so i am very reluctant to pay for it myself.
i can live with it as i use mine as a weekend toy, when i come to sell it early next year i will remove all the mods and put it back to standard and trade it in
let the lucky new owner deal with it
