citroen xsara picasso rot

seeing more and more of these and the equivalent pug/fiat versions approx 96-04that use the same floorpan(406/multipla and the vans derived from them)with rotten sills,look fine visually as they rot from the inside and have a nice thick layer of paint/stone chip etc from new but when tapped(especially at n/s/f)there can be no metal at all underneath,its a rare one when you dont at least hear the rust rattling around!have been pulling these for about 4yrs now so you guys have probably already seen what i mean.....