Older cars used two piece molded rubber to mount the windshield glass panel just like the jeepneys', subsequent years, with an effort to reduce weight and reduce air drag used butyl bead adhesive between the windshield frame and the glass. Today's cars use polyurethane windshield adhesive. It is necessary that the windshield frame is free of rust, oil and debris for proper sealing and adhesion. Lifting the car at any one corner in excess of how much the jack that came with the car sometimes cause this adhesive to delaminate so that the next time it rains, it rains inside the car too. You can confirm where the leak is originating from by introducing smoke from a smoke machine. If the shop does not have a smoke machine, you can use food coloring or any dye and try to simulate rain pouring on the windshield