I've read a few posts like this. You should always top off the carboy to about 4 inches below the bung. What was mentioned about the mold, is to carefully rack wine into a clean carboy without transfering any of the mold. Filtering it would help as well and top it up this time. I forget it you would need to add any more K-meta or sorbate. But don't throw out wine it should still be good.