Rallonge de tige à trois fonctions pour douche à jets RP37902

This thing always had a sloppy, wobbly action, until it broke. The pieces show that the plumber must’ve cranked that Allen wrench hard, to screw through the plastic, because the tab on the handle doesn’t fit snugly into the slot on the piece. No wonder it’s been discontinued, and the non-compatible new ones seem to have brass parts, but I can’t find any that fit RP 37902. My plumber said he’s never seen a part discontinued without there being a replacement, and this plastic part is truly a bad design.