So what your saying is that at full speed, you flipped, slid on your roof(providing absolutely no way to slow the car down), and hit the wall with the back of your car. The end that has no bumper to protect it (nor do 99% of other cars out there. And you had some significant damage. I would expect so. With the kind of hit you describe, Im suprised there is a broken chassis as well. I dont think any car would withstand that kind of hit.
But then again xray T4's were shredding chassis at the front bumper mounts and nobody seemed to complain. Its just part of having an xray I guess. We will just through a bumper brace on it and all is good with the world. It seems some companies can do no wrong, while everyone else is still held to thst percieved high standard. I have had very few issues with my VBC's. Especially since the V2 plastics. Oh and I stopped hitting the wall so much.