Did you get a genuine bosch regulator?
When I had this problem my car had a no make regulator on it that would only put out 12 volts which is not enough, voltage needs to be over 13.5 running.
I replaced my regulator which fixed the issue for abit but then started to have problems again so I bought a reconditioned alternator which had a genuine regulator on it but would only put out 12 volts so I had to swap it for my replacement regulator and I've been OK since,
My experience these cars are fussy about the regulator, you can test resistance on your regulator with a multimetre which will confirm that it's broken,
Plenty of videos on YouTube explaining how to do this.
Also use electrical contact cleaner on the connector to the regulator to make sure your getting a good connection, I kept getting a bsd fault till i did this.
One last thing I replaced my alternator because the slip rings were heavily worn if yours look like this then I recommend a new alternator or getting yours rebuilt as suggested by colb.
One last thing If your