Front Suspension Wheel Bearing problems of the 1999 Mercedes Benz E320

Front wheel bearing on car exploded causing damage to hub and spindle also damaging brakes. This incident happened on the right passenger side and last year on the drivers side. The first incident happened at 50,000 and the second time happened at 60,000. It is a contained unit, so it can not be maintained as though you could just add lubrication. Service dealer was surprised at how this occurred at such low mileage.