Ask Gamblers doesn't want to get involved, and Casino Guru has rejected your complaint stating there is some evidence that shows a connection to other Stake accounts. At the same time, they have no reasons to believe the submitted KYC data is fake.

You have already spoken with their licensing authority and gotten no response from them either. Have you tried reaching out to the Crypto Gambling Foundation to see their opinion? You can find a link to their website at the bottom of Stake.com or simple go to https://cryptogambling.org/contact/ and check it out.