Battery and Electrical Problems

[Bruciebonuz]

I have a 2002 3.0i which has had a recurring problem.

My wife was driving the car and everything died, SATNAV, lights, indicators, PAS and then the engine cut out. BMW replaced the alternator.

Week later, sitting at home, we hear an alarm and go out to the car - unlock it and alarm goes off, try to start the car and its dead again. Jump start it, leave it running and its ok. Next morning try it and its still ok, go back 3 hours later and its dead. BMW come out and say we must have left something on, charge the battery and vamoose. Wife goes out in it, electricals play up - stereo and NAV go off, indicators pack in but car keeps going until she gets home (whether it would have packed in again we dont know)

BMW take it away saying there is a General Module coding problem. Two days later they call me to say they cant find anything wrong.....and then the just call me to say the new alternator is broken so they think the battery is faulty. But each BMW Assist guy has said the battery is charging fine.......does any of this ring any bells?

Thanks all.