Rear Speaker Brackets

I recently purchased a 1989 mk2 Polo, and the previous owner had upgraded the sound system. While I do appreciate the sound, the old rear speaker brackets for the 4x6's that the seat belts go through have been partially destroyed. I can't seem to find any replacements online, but I'd really like to put those back as the rear panel isn't held in place very well. Does anyone know where to get these or have some going spare from their own changes? Any help would be appreciated.