Not sure if it's still relevant to a MK7, but when I had my MKV Golf, I had a shopping trolley dent just ahead of the fuel filler flap in the middle of the rear panel. My PDR man jacked the car up, removed the rear wheel arch liner, and there were then a few large grommets which one of them when removed allowed him to get his PDR tools up inside between the inner and outer skins and did a perfect job, Grommet back in, wheel arch liner back on and job was a good one.