Electric Parking Brake
Mine was a nightmare to begin with, failing at junctions and leaving you stuck!
I only ever had two issues with mine. One was the price of the oil, could only be sourced from a VAG dealer and was something mental like £20/litre, the other was the parking brake occasionally failing to release. It once did it as I was at the front of the queue trying to disembark a ferry from Ireland; if you were behind me that day, I'm very sorry.
Couldn't tell you what revision it was, would've been something like 2005-6 vintage.