This is a sort of follow up to a digression in one of my other threads, but I now have enough data about the problem to finally maybe get some help from you all. I put a skidplate on the bottom of my 05 RS wagon. Two of the three front bolts never got tight. At the time, I thought the nuts had stripped and I planned to re-tap them later. After some miles with the skid plate on the car, we heard a pop-bang and then rattling one night. When we got home, I saw the passenger side bolt hanging loose. I figured the nut had broken its welds and come free. I managed to wedge then nut against something and remove the bolt.

Today, I removed the skidplate for an oil change and was dismayed at what I saw. The nuts have RIPPED OUT out the subframe!

The passenger side nut has ripped completely out and is MIA:

The middle nut is holding tight for now, but I see cracking that makes me think it will soon rip out too:

The driver's side nut has ripped out, but not yet come free of the shards of the subframe:

How on earth do I fix this? I can't just weld nut to the bottom of the subframe because there's no solid metal there. I could buy a new subframe, but they're over $350. I suppose a big chunk of the subframe could be cut out and a new bit welded in, but that's WAY beyond what I'm capable of doing and I have no idea what kind of a shop to go to to get this done well.

Any help?