shoddy quality of concrete slabs

terrible products . put a precast concrete wall 2 years ago. the slabs are getting brittle and breaking. holes are forming and sand falls out the holes. the walls are turning black and look disgusting. the owners words after calling him to have a look at the wall. he cannot do anything and i must repair and paint the wall at my cost. and the wall is only 2 years terrible customer service and terrible quality of the slabs.