I just replaced my plastic hinge for the second time. The good news is that there is an aftermarket piece made by Dorman, part number 924-141. Most auto parts stores carry Dorman products and can order it in for you. Cost is in the US $4 range. The bad news is that it is made in China and is of the low quality that you have come to expect from Chinese products. The problem is that the 4 plastic pegs that you drive in to hold the bracket to the body of the car are not factory-seated far enough into their holes, so that when you try to drive them in, they go sideways and come out. In order to successfully install this part, you should get the pegs started on the workbench before you try to mount it on the car. This can be tricky even on the bench. Work in a clean, well lighted place, so you can find the little black peg if you drop it. I found it sometimes necessary to install the peg from the bottom and drive it up to its proper starting position (just above the point where it spreads out the 4 fingers that holds the bracket into its mounting holes.) Be careful not to break off any of the fingers.

If you have easy access to a dealer, I suggest buying the original one from Volvo. Those work the way they were intended to work.