Only my wallet !!
In low ratio it the torque converter would win.
I've always thought hill start assist would be a waste of time on an auto.
Given the low proportion of people who buy autos I suspect there are not many people out there with your experience. So we can't really say whether it is a fault specific to your vehicle or whether it is an inherent design fault I can only suggest you are now in the area of fitness for purpose or whatever the correct term is and approach it from that angle - say to VW (in writing) fix it or have it back.