Did it post as an online, signtaure type transaction? If the website is not Verified by Visa, you would most likely have chargeback rights for 'unauthorized' against the transactions that cardholder claimed they did not perform.
John, unfortunetly, the casinos know that just about every card issuer prevents activity at MCC 7995, online gambling, so they use other obscure MCC codes. But the good news is, if you can prove a loss due to fraud or collections there are some compliance rights to go back aganist the merchant since they did use an incorrect Merchant Identifier if you can show you would have declined the transaction if they presented it correctly.