I had carrara marble tile installed on my bathroom floor and standing shower and there are a significant amount of grout lines because of the tile size/design. The tiler I bought the grout from gave me Grout Boost and assured the grout would remain the original color with regular cleaning and whether the installer failed to use the product properly or something else, the grout has stained in many areas and not others leaving an inconsistent finish. I've attempted to use several different cleaners to no avail. This is admittedly very frustrating. Does anyone know of a method or product available to get this grout back to it's original color consistently around the bathroom? I'd be VERY grateful for expert solutions.....