This is my first post so here goes. On my galaxy it was the drain off pipes that connect to the gully on the sunroof that had come off and were allowing the water to run down the roof and door seal under the carpet and in to the comparment under the passenger seat. Once i pushed the pipe back on it stopped. It a bit of a tricky job to do as you have to get between the roof lineing but it will fix it. Hope that helps.