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I suggest you to create a scam accusation against them in this board:
https://bitcointalk.org/index.php?board=83.0 Dont forget to check the pinned topic titled "Scam Report Format", simply use the format provided on that topic to explain your situation.
Or maybe you can try to use casinoguru, as they may help you to get in touch with the official representative of rainbet.
Although I doubt that they can help you because there is also 1 complaint at casino guru which is also related to the sports betting and casinoguru said that they cant help much for sports betting related issue but trying is better than not doing it.
should do this right away, so other players on their platform is being warned by their practice. If he feels, he didn't violate any of their protocols, he should fight his case. Because if this will continue, they will screw more players on their platform.