Alternator/generator/regulator problems of the 2002 Mercedes Benz C320

I have a 2002 mercedes c-320 car that the battery will not hold a charge! I had the mercedes dealer come to my home and put in a new battery. After spending $300 and 2 days later the new battery was dead. I was told it could be the alternator/regulator by the mb dealer and the cost would be $1,200. I took it to my local mechanic, who works on for. Cars, and they replaced the alternator/reg. For $512 out the door. 2 days later the battery was dead again. I was told my new merc. Battery was not good and they replaced it. 7 days later my battery died again. My local mech. Told me to take it back to the mb dealer as there seems to be a problem with their module and they should replace it for free as through his research many individuals are having the same problem. Clearly a defect part by mercedes as through my and my mech. Research, the mb mech are replacing the old modules with a new and improved one to fix the problem. I now have now had aaa to come and charge my battery once again and I will take it to the mb dealer. I hope they a will do the right thing.

Car stalled in the middle of the road and almost caused an accident. After 15 minutes, car started back. I had it diagnosed and a module was replaced. 2 months later, the battery started draining. I had the alternator replaced and the battery twice. Car will work for a day or two and dies again. So many other mercedes owners of C320 are having the same problem. Battery dying and car stalling.