Another things is that the representative account has been inactive for quite some time now so I dont think theyll be able to get any information about this thread and since he (the Op) already tried telegram he should also include the link to this thread and see if theyll be any difference.
I saw this similar thread on the gambling board. If the accused account, which happens to be the casino representative, appears to be inactive, I think either the OP or any member can just send a PM here on the forum.
If they happen to use a valid email, at least the mail notification could be able to drag back their attention here on the forum, as the PM will be detailed enough with the accusations thread included on it, as there have been many cases of that nature where the accused happens to be inactive, and PMs usually trigger their attention. This method can be used if their support fails to respond through Telegram.