If you think it's worth trying and don't mind me to try reaching them, though, please send me a PM with the contact details, I'll try to nudge them.
I have got the telegram contact of Denis. Unfortunately, he doesn't reply me anymore neither he check my message. I'll send you the telegram username shortly.
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Thank you, PM received. I'll try to reach him, hopefully we can get him back to this forum.
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Your best option now is to file a case with Guru Casino, as suggested by some users before, and hope for a response. If they do respond, the Guru team will reveal the truth behind what happened to you exactly.
OP already did, though the casino itself has yet to reply to the complaint. Here's link to his CG's complaint:
https://casino.guru/coins-game-casino-player-s-account-has-been-banned