The problem is here that I can just see my betting history. There is no such Casino's History. And how can I prove this? I asked 1xbet for details on money cashed in slot game, but they didn't respond.
Sorry to hear that, if you don't find any solid proof there's nothing you can do just move on. Besides, you are not the one who scammed them, there are a lot more even though in searching on google there are more unresolved scam accusations against this gambling site.
This serves you a lesson that you must to learn, do research first before using any gambling platform. You don't have a loss here because that's all you've got from winning to their site so nothing to worry, you've effort has been wasting but no fund from you are being stolen.