If the door is still manufactured, we can replace the bottom section in most cases.
If you can find a manufacturers sticker(usually on the side of one the sections) on the door with make and model number we can find out if the door is still available.
If it is, you’re good to go. One issue we do see when doing this is that because the new section is right from the factory, the color will not be an exact match to the existing door sections because they are weathered. So painting the entire door will likely have to be done.