True, i've got the same problem, the body rolls like an old boat on a stormy sea and it bottoms out on even the smallest undulation in the road; great fun going over the A57 Snake Pass.
Thankfully i've got a new pair of springs ready to fit. Just had some U bolts made up by Owen Springs:
http://www.owensprings.co.uk/
Decent bunch, they even remembered the specs for Marina springs from back in the day.