You can blame the
"tiler" for poor fixing, but not for poor tiles.
And 90% of tiles from B&Q are poor, in my experience.
If the main issue you have is with the tiles, take your complaint to B&Q.
If it's with the tiling, take it to the fixer.
One other thing, shade variations in white tiles can be hard to notice before grouting. Even though it stands out a mile after the grout has been done.