I would be looking at things on the ground side of the system. The only time I have ever had an alternator go bad that many times, the engine ground was none existent. (completes the circuit to the alternator). but with a car like this, the ECU would show other issues with a bad ground.

I also don't know if you have a parasitic draw issue or what you are describing, but the fuse box sometimes "melts" to allow bad things to happen.

I recommend a good electrical shop as well.