I just had an installer begin work on a large bathroom floor in a clubhouse on my farm with black/white checkerboard tile with black grout. He left the job because he was sick without telling anyone. He also left grout all over the white tile...didn't clean it at all. It's been there for four days...we discovered it yesterday. Needless to say, it's difficult to get off, been scrubbing like crazy. But the tile is stained. It's not a sealed tile. Any suggestions would be appreciated!!! Thanks in advance!