Not obvious size differences

When I researched buying Revelstone Kent tiles, the web technical information page says 500 x 500 x 20 for the square tiles, and 500 x 400 x 20 for the bullnose tiles. On this page, nothing is said about any dimensional variances (nor on the eventual quote). On installation I see that the bullnose tiles are closer to 490mm (so grouting lines do not line up). After phoning the sales manager he said that they do not guarantee the same sizes, as their website says they are hand made, so not the same. I searched the web site, and found, under the resources page a document called 'Product Technical Information' where it says that: 'All sizes, dimensions and weights in this brochure are nominal and subject to manufacturing tolerances' without any actual tolerances quoted. Hiding the manufacturing size differences like this is not acceptable for a tile product that costs so much (I could understand the difference with pavers, but not tiles).