Well bal and topps will feed you a load of crap about how you can't wash away their pigment as it's chemically bonded to the cement particles, which supposedly is what makes their grout the best, although we all know how reliable a claim that is now, so who knows really. I have had a colour uniformity issue with mapei before (if the bag isn't shaken up properly before mixing) but never with bal so it may be true to some extent, although I'm sure it's not as perfect as they suggest. Mine did stay pretty black, but it is quite normal for grout to absorb some water and look darker when wet so I wouldn't worry too much. The main thing is to stop it from bleeding and sure up the surface. Either way you should start to see results by Tuesday morning, maybe do it a couple more times that day if it is significantly better, that should be enough by then hopefully. If it's still bad by Tuesday you can keep going and hope it works soon, or try one of the grout sealants, but I can see why you are reluctant to remove the grout, those tiles are pretty small, it'd feel like a lifetime redoing all that grout!
I do dislike topps too, especially now, but too many customers go there and pick tiles before I've even looked at the job, maybe I need to be more assertive, I also need to find a good local tile supplier, they seem few and far between round my way.
