Tailgate problems of the 2003 Jeep Liberty

There is growing rust on the back of the vehicle, on the roof panel, just above the tailgate window, on the driver side. It started under the glass, inside a weld point. Every body shop expert I have every taken it to says the same thing: this was a bad weld and water was allowed to get in there and under the paint. It started with a tiny bump years ago and is now the size of my hand and growing. My concern is I have seen this on at least four other Liberty Jeeps. A post on Jeep's facebook page also turned up a few people with the same problem.