Gwalior Stone on Elevation of our House

Dear Sir,

Recently, our house was constructed by a Builder where he has put Gwalior stone on the Outside walls (Elevation) of the house. They had put some clamps and other things for fixing up the stones firmly. However, we found that 2 slabs have alreday fallen. How can we ensure the safety that no slab falls in future though i understand that work has already completed and there is no question of using the better raw material for fixing it up. Pls suggest if any remedy is possible on the existing setup? 

Regards,

Sameer