Sorry to hear of this dilemma..........HG do an impregnator for marble...also lithofin stainstop is good as well.......but as mentioned mixing sealers doesn't work.....
I would contact HG and see what they recommend to use to remedy this problem.......
You can phone them on 01603 714341
or you can email them direct >>>
HERE<<<
good luck and let us know how it goes........
