2003 Volkswagen TDI charging problem

So a week or two ago my mechanic replaced some struts on my car right before this I noticed that one of the pulleys on the drive belt was making a horrible sound. I asked my mechanic he said it "wasnt a big deal" knowing minimal about cars but also enough that I didnt trust his judgement I told him to drive it first. Upon first drive after struts installed (dont know if related) the car needed a jump, starter sounds fine when charged just a clicking indicating not enough amps. So sure enough I thought battery or alternator took the battery off got it tested it was original, replaced it and bought a alternator. All seemed well except when he replaced alternator female electrical clip was damaged, my mechanic assured me the heat wrap and zip ties he used to secure the clip were sufficient but now im stranded again because of charge. Before car stopped lights began to come on in dash, and radio flickered, lights dimmed and I knew what was coming so I pulled over and tried to fire it up to no avail. Suspecting the alternator clip I also wonder if the voltage regulator is located inside of this peticular alternator (bosch 120 amp). Battery is literally brand new and bigger then original but recommended by shop. I know that maybe a light or accesory is triggering over use but I figure that would overstimulate the system instanteously. Help me im stuck and pissed at my mechanic!

thanks,

dan