I continue to be amazed (appalled actually) how bad so many of these outfits are. ANY code is electrical. The charging system is what provides electricity to the vehicle. I guess 2 + 2 doesn't equal 4 for them. Sure, the code might not be caused by a faulty charging system, but to NOT just automatically do a simple load test on it? However, they tell you to do a chain job for $2300, with barely any diagnostics at all. Wow, they are SO WEAK.
And just an FYI that starting fine doesn't confirm that a battery is completely healthy. And a code being set can be a possible symptom of a bad battery - certainly not always or even most of the time, but a possibility nevertheless.
I take it you don't have a multimeter, so definitely take it somewhere to have the charging system tested. And if it's not too inconvenient, you might want to test it at 2 different shops or auto parts stores, because there have been cases reported where certain testing machines don't catch every issue with the battery. Again, I'm not saying this is what's causing the code to be set on your vehicle, just that it's a very basic, standard test to do, early in the diagnostic process.