Change crossbars

Hello, I know I won’t let you rest, but until my little one is over TÜV I have to do a whole lot more. The next thing to do is the crossbars. The bushings of the crossbars are broken. With my dangerous half-knowledge I would now simply say that it would probably be easier to change the whole crossbars than just the bushings. Did one of you ever do that? Do I need special tools there? Does someone think that the crossbars in ebay are much worse than those of ATU? Thanks for your answers. Matthias