Ugh.
You might try one of those "magic sponges" ... I have had better luck with those that anything else, including heavy-duty Goof-Off.
My 2 Year-Old got hold of a Sharpie and decided to colour on Daddy's brand-spanking-new notebook. It hadn't been sitting there for years, but the magic sponge cleared it up beautifully.
Failing that, I have (long ago now) soaked such stuff with Goof Off with reasonable results.
Good luck & Cheers.