~snip~
The only answer to the OP question was the license commission or on the department of anti cyber crime on the complainant country.
Here is how to report international gambling fraud.
https://www.wikihow.com/Report-Illegal-GamblingAnd here is where to report gambling fraud.
https://www.ic3.gov/Home/ComplaintChoice/default.aspxBut always remember to have compiled all strong evidence you have and that is very needed to prove on their fraud activity and quickly shutting down by the authority was there were caught. Most likely file complainant does not want to proceed because this is a very long process though there are too many cyber crime authorities who will help you but there is no guarantee.