I'd have to look for it, pretty sure I posted a thread about my front windshield leaking at the lower seal and the trials of going back and forth to the dealership until they solved it by replacing the windshield, which was what i asked for in the beginning. Now in my case the front drivers side was getting wet, but I could also see and feel water dripping at my feet. It was pouring down over the dash electronics and hitting the floor. I usually got the car under cover quick and sopped up the mess quick too, so it never made it to the back seat.
All my point here is, it could be possible that it is coming from the front of the car, getting under the carpet, as the carpet had a rubber base under it as i recall, then water is coming out through the cut's under the drivers seat for the vents and what not. You said at one point water was up front too...I'd have to lean that way again myself. Here's the thing, if the dealership isn't getting it done, get hold of the Kia Preferred service, they will work with you and get the dealership to take more chances with these fixes until they do solve it. But again, going back to my dealership, they had a "leak Expert" look over my car twice, said initially it was the power wire i ran through the rubber grommet to get under the dash. It actually took me driving over to the dealership in the pouring rain, get it under their cover, pop the hood and show them, look bone dry everywhere around that grommet for about 3 feet or more in every direction, but under the dash it was dripping...I said look, it's my belief this is the windshield and I want you to replace it under warranty and they finally did. When the windshield guy got there and took apart the moldings they could see plain as day where the problem was coming from. Pulling the old WS required them breaking it, so having the new one on hand was paramount, and they sealed it up nicely...never leaked again. To note based on their initial inspection of everything on that last trip, it was pretty certain that this was a factory installed windshield, in that it wasn't replaced before I bought the car used...therefore not a 3rd party's fault but a true warranty issue.