I purchased an A6+ miner from them on 5/30/2021. The total was just over $2900.
Since then, they have replied to no emails and no support tickets. Upon looking into things further, seems they are on a scamming spree. Negative reviews are popping up everywhere and all with the same story. No one replies to emails and/or tickets. I used Coinbase to pay and they have been notified of the scam and are investigating. I contacted the Swiss authorities. Seems Prominerz has started a lot of scam companies under the name "Stoffel" that are no where to be found. A report has been filed with the FBI cyber crimes also.
Their phone number does not work. Their address is a lie. But I am slowly finding more out daily to help investigators bust these scammers. Judging from all the people they have scammed, I'm guessing they have stolen hundreds of thousands of dollars from people like me. More can be found on the ProminerzScam.com website.