Inca Blue honed stone tiles

    
What kind of stone is Inca Blue? We selected this beautiful stone for our bathroom walls and it was spectacular. However, after a few months, the stones began to show a pattern as if they had been wiped with something - swish marks. Over time, this has become worse and the tiles are definitely looking unevenly discolored with a dull whitish patina. This week we just realized that what looked like some kind of soap scum at the bottom of the shower is actually a pitting and deterioration of the stone.

When we first noticed the "swiping", we had the contractor come back in and he tried to rub it out to no avail. It was his opinion that our cleaning person used some product that damaged the tiles. We doubt this as some of the damage is higher on the wall than she ever (unfortunately) cleans. She also swears that she has used only mild products designed for granite and marble. When we noticed the deteriorating tiles, we again had the contractor come in and he said he would replace those, but insisted that the discoloration and "swiping" patterns were our fault.

Can this damage be fixed or do we have to replace the entire bathroom tiles?

If you can give us any advice at all, we'd be very appreciative.