The regulator has not been replaceable in my experience. I am sure there is a way but none of the parts chains I checked carry just that. 15+ volts is too much, at 16v some things will start to break, mostley computer controlled parts that dont regulate themselves. At least they are sending you out a new one. You could swap the regulator out but I would just change the whole alt over. As Shawn had sai it may have an internal problem that caused the regulator to burn out.