Brakes, rear suspension and 520

Hey folks,
#324 is still going, but now up and imported to Canada, between Ottawa and Montreal.

My 12v battery died because the cabin fan stayed on, without my knowledge, and it lost its software. I had Montreal dealership reflash 520, but the backup camera isn't working, the stereo sounds like crap and I have no NAV. I'm headed back there on Tuesday. Years ago, the 535 update caused a parking brake error that bricked the car.

I asked for a diagnosis of a dragging sound and they came back with a long list, including needing new pads/rotors all around (not a big surprise), new rear struts, bushings, rods...pretty much the entire rear suspension (really?).

The suspension feels fine and the car brakes fine but I suspect the brakes are what is dragging. I've never braked hard, using regen as much as possible. Am I missing something? The cost of all these repairs are considerable and I just wanted to know if these are typical for our cars. I do now have 125000+ km on the car. I'm still getting 85-90% of my range, even though I'm on my 3rd charger.

Can I change the brakes myself or even get parts? Will there be damage, if I hold off on suspension repairs? What's typically replaced? I did the "jump on the rear bumper" test and the suspension corrects itself quickly.

Thanks much.

Alex VW