I did consider a grout sealer on the rest of the bathroom as it would take quite some time to do the clingfilm technique on the whole bathroom.
Can you recommend a grout sealer? There's so many out there I don't really know what's good and what's not.
The quality of the tiles was not fantastic to be honest, the customer bought them without me, which I wasn't thrilled about, but I never considered the tile to be at fault for the grout. I did a small patch of the tiles behind the mirror in the downstairs toilet, grouted with black mapei leftover from a job a few weeks back but had a slight issue with colour uniformity so decided to change back to Bal for the en-suite. Wish I hadn't now but I guess it's a lesson learned, I'll have to give tilemaster a go on the second bathroom, which I start next week.