Renault r19 Cabrio cloudy rear window

My daughter recently bought a convertible Renault R19. With this vehicle the rear window is so cloudy and scratched that you can no longer see through it. On the Internet a company offers a complete cover with a glass pane (with test mark, i.e. with the snake line) for purchase/installation. This disc is therefore not made of plastic and therefore “cloudproof”. Since the cover of our vehicle is still in a very good condition, possibly only such glass Has anyone from the Motor-Talk-Forum already made a rear window change (in particular installation of the above mentioned glass pane) at the R19 convertible? If so, what is there to consider? Are sources of supply known? How expensive is the disc, for example. I would be happy to receive answers and would like to thank you now.