Car shutting off while driving

When I drive my car it will act like it’s losing power. The radio shut off and then stabilitrak message came on about 1 minute later car completely shut off. Advance Auto Part said he was getting about 12 testing thought it could possibly be alternator. Chevrolet manager told me yesterday probably not. But they are still trying to figure out problem. A month ago my outlets didn’t work they replaced fuse upfront for those and replaced i think a relay for the back middle seat power plugs. Once again the back ya gone out again and then this happened. Might be 2 different issues.