I understand how brakes work, as I've replaced and re-built many braking Systems along the way, including GTI's. I'm not some uneducated, non mechanical person. I have a big garage with a lift, which BTW you're welcome to use if u ever need have a need for it. I do all of my own work on all of my vehicles. My MK5, my 2016, and all of my friends GTI's brakes do not sound like my 2017. The Hill Assist system (at least I think) seems to stay engaged sometimes on flat surfaces and when I start to move u can first feel the rear driver side caliper hanging on a little and then makes a very loud bang/twang sound before releasing. I have not had much time yet to do much research but just from googling the "brakes making a grinding noise". Many others are having this issue, and for some of those that brought the issue to the dealer, some of their cars had their rotors replaced, and adjustments made to the calipers as well.