I haven't hear anything 'new' about 'fixing' this problem in about 5 years. So in the meantime, 'they' may have come up w/a solution. Based on my current knowledge, you're out of luck.
HOWEVER, today, there may be an acid, or etch, that you can buy to remove the excess grout and haze. I'd visit a local Plumbing Supply Company (found in the YELLOW PAGES under PLUMBING -SUPPLIES) for guidance. Be prepared for toxic fumes and the need for gloves and so on!
I wish you well. My best to ya and hope this helps.