i remeber stripping 1 of thes down a few years ago now for what sounds like the same thing,
the set up is just like the pugs/citroens, height adjustable torsion bar
i got bushes and fitted them but the kept coming back out on re assembly, were very slack in the housing,
i then spoke to somebody at the dealer who said it was very common on the needed to send the beam to an engineereing shop who machined out the housing and pressed in a new insert,
sounded very expensive so i just sourced a 2nd hand rear beam and fitted that,
i think that might be your best bet as well mate