All legal online casinos for real money operate from a specific country or jurisdiction. To operate an online casino, gambling must be allowed in the country. Licenses are issued either by the state itself or by a jurisdiction that is interested in international business (Malta, Curacao, Gibraltar, etc.).
If the casino https://catscasinos.co.uk/real-money-casinos/
refuses to pay money, then you can file a complaint with its regulator, who issued it a license. Of course, the regulator will always be on the side of the casino, but a really good regulator will assess the situation objectively. In the event of serious violations, the regulator may even revoke the casinos license. Good regulators include Malta, Alderney and the Isle of Man. In the event of a conflict, there is a chance to achieve justice.