Crappy parts store voltage regulators

Got 2 different regulators from advance auto and they kept over charging at 15.6v. I found and old wells regulator that says made in USA in the bottom of my spare parts drawer, sanded the edges for good ground threw it in and now car charges at a steady 14.3v.

The kicker is advance wont return it for my money back only exchange for another because it's an electrical part.