Black mould spots on my current bathroom tiles...? hello.... i have just this minute had a untried bathroom fitted and...

hello.... i have just this minute had a untried bathroom fitted and have started to see small black mould spots on some of the tiles... the tiles are not the smooth type they are textured so the mould seems to be ingrained contained by the tile how do i remove it i have tried the usual mould removal potions and a apt scrub with a staple brush and bleach but this did not work.. can any one help me carry rid of these black spots that seem to be growing within numbers... many gratitude..
Answers:    Try using neat bleach (as Domestos, Parazone). Wear polite rubber gloves to do this. Is your bathroom unheated?, mould grows in sodden conditions.
You may try Tilex, but if the bleach did not work this may not either. If you have someone do it, I would call them subsidise out and show them as there could be a problem near the installation. This should not be happening on a bright tiled floor.