Well, your Ford escape is a unibody style. So yes, they can replace the rails. It is very labor intensive and requires removing the rear suspension, maybe the fuel tank, and a few other things. I have the entire frame on a silverado diesel once and that was a huge job.
They can be replaced, but cheap it is not. It is a very labor intensive job. Replacing the rear frame rails typically involves replacing the rear floorpan and rearbody panel as well. All the rear interior trim must be removed along with the fuel tank and rear suspension. Just going off the top of my head I think it is around $3000-$4000 to that.
This is not a repair to be attempted or performed by amateurs.
