When my shower door frame was installed, the frame was too short so there is a 1/4" gap on one side and a larger one on the inside bottom corner. This came to my attention when I had a leak that needed to be fixed. I removed the old material and recaulked around the door frame but the caulking only lasted a few days before it started getting soft and runny. Obviously they had filled the gap with some other material before caulking. What product can I use to fix this? The drain holes are clear but some water must be sitting in the frame and breaking down the caulking.