I have read in the past a couple of threads on iirc a skoda forum that says due to the rear ones not been re-enforced metal if you jack at an angle with a trolly jack you can bend that panel.
A simple solution to using a trolly jack is shown on this skoda thread below.
http://briskoda.net/forums/topic/149492-jacking-pad-for-trolley-jack/
Just stumbled onto this thread during some googling and thought I'd add my tuppence worth.
These jacking points are not great for long term use if you regularly adjust coilovers or do oil changes every 3-5k.
I think these 'jack points' were actually just for moving the body shells around the production line in a jig. They will eventually cave in, as what happened to my MK4 using these pads.
The pinch welds on the sills are the correct and strongest place to jack the car up from, so I would encourage folk to not to use these jack pads.