Although we do not know the details, they too may have ignored the OP's request to exclude his mail from the advertising mailing list. But in any case, for reliability, it was necessary to block all incoming letters from the casino.
I think maybe the site has a particular timeframe that those messages would stop coming. Op didn't really say what the problem was and how long the problem happened but in any case he has informed the service to stop servicing him , that should actually settle his case as he is no longer interested as he is going away from being a gambling addict. I do understand however that they own him a responsibility to deactivate his account for further messages by themselves.