The only leverage you might have now since they are deneying it and already have their money is to start placing bad reviews of them online.
Top review sites are Google, BBB, Yelp, Houzz and Facebook ... read more
The wash the brick mason is talking about is an acid wash. That should take care of the white stains. As far as the vertical brick looking a different color, the acid wash should take care of that too ... read more