If that doesn't work soak in penetrating oil leave for an hour or two, Jack up the car both sides , get a brass bar about 12" long, screw a bolt into the end of the torsion bar, tape and pad up around the rear wheel arch adjacent to the Torsion bar to protect it. Get a lump hammer and the bar and give it some one side and then the other until they move off the splines ( on the R5 there is a spacer in the centre, don't loose it.) Not sure if there is one between the torsion bars on the Clio I would assume that there maybe. I tried the socket and bolt malarky and couldn't shift mine. The lump hammer did it for me.