Cleaning newly laid encaustic tiles

[Dan45]

I've had encaustic tiles laid in the kitchen. Despite my instructions to keep them clean, the builders have tread a lot of dirt into them, which I'm trying to remove.

It's quite possible that the tiles became dirty before they were sealed. He has tried using a floor cleaning machine which hasn't worked. I've tried Lithofin MN Powerclean, 3 times on the same area, but still no help.

Here's some photos of what it looks like now. I've put a new tiles on the floor in some of the pics, to show the difference in colour:

Is there any other way to remove these stains, or do I have to either live with this or replace them?

Thanks

 

[Tigercubrider]

I would ask the manufacturers

IMHO if the builder cannot rectify it then he owes you for new tiles
There is a big scratch on a couple

 

[Dan45]

The suppliers told me to use the Lithofin MN Powerclean, but obviously that isn't working. There's also scratches on a lot of the tiles: