1995 Peugeot 405 diesel elcetrical problem?

Problem: car runs ok then Air Bag warning lights comes on, at the same time the temp guage goes to zero and the cooling fans come on full blast, and the fuse blows on these cirtcuits, replace the fuse, lasts a few miles and problems is back, run the car and the battery goes flat, not enough to charge it, had garages look at it and no-one can resolve the problem. Any ideas appreciated?