as I've suggested earlier: Release the initial deposit and then investigate the winnings later.
They can't do that because they said:
There have been several people from different territories contacting us via different channels to claim ownership of the account, with varying degrees of evidence provided.
But Ronnie doesn't want to talk about:
Regarding 330BTC scam accusation, how many people actually have access to account?
Has OP stated whether the funds can be returned to the address that they came from or not?