I think you would be more likely to succeed if you focused on fixing the way outcomes are determined in your casino so that they are actually provably fair.
In the mean time, you should remove any mention of your games being provably fair, since they're not.
Your issue with their provably fair implementation is that the client seed isn't used for the generation of their server secret, but is instead used to manipulate the final results. In the case of a card game, that means cutting the deck, and I see how that could be exploited. I'm not sure how that'd be implemented with their slots game though because it seems like the client seed does an unpredictable job of shuffling the reels, and same with dice. Do you have any ideas on that? (I really am just curious, not trying to defend this casino)
Anyway, this casino failed to process a withdrawal.
When the casino isn't even provably fair, withdrawals should be the least of your concerns.
You'd be pretty stupid to play on this site imho, at least play at a place where you know exactly what your odds of winning are through a provably fair system.
But hey, each to their own I guess.