When I owned my mk6 Golf GTD, I had 2 wheels replaced under the 3 year factory warranty. They were diamond cut alloys that had suffered from whiteworm corrosion due to a manufacturing defect.
Whether or not you may be successful getting a claim submitted under warranty will depend on which extended warranty you have;
1). if you bought the car used and it had VW's Das Welt Auto used car warranty, this only covers electrical and mechanical failures, so wheels wouldn't be covered.
2). if the car's warranty was extended at the end of the original 3 year factory warranty by the purchase of a VW Extended Warranty, this also is a warranty covering electrical and mechanical failure, so wouldn't cover wheels.
3). if you have the benefit of the Extended
Factory Warranty, this may cover the wheels as it should give exactly the same warranty cover as the original 3 year warranty that came with the car, but had to have been purchased when the car was originally ordered / bought new. If your extended warranty was purchased at a later date, you won't have the benefit of the Extended Factory Warranty - you'll have an electrical and mechanical failure warranty that wouldn't cover the wheel damage you're experiencing.
If you have number 3). above, it's worth going to your dealer and trying to claim for new wheels. At 19,000 you may still have the original tyres on the car, in which case the bubbling around the tyre valves is likely to be due to a manufacturing defect rather than tyre fitter damage.
If based on the above, you conclude you don't have warranty cover for your wheels (or if VW say 'no' to your claim), then you could consider getting your wheels refurbished. One wheel refurbishment company that pretty much always gets very good reviews on this (and other) forums is Lepsons (
www.lepsons.com). They're based in Gilligham, but if they're not local to you they often offer a free courier service.
Good luck!