You are a Diamond III player, so they should have been a bit more accommodating to you, because you have shown that you invested a lot of money and time into their casino.    Unfortunately, we do not know why Stake support handled it this way, because a $400 loss.. would have been nothing to a casino of their size... and also to lose a high roller like you. 

I would have liked to hear the Stake Support side of this, just to be fair that both parties had their say... but I guess this will not happen. I hope you get this sorted out.... and that you stay with Stake, because they are much better than a lot of other casinos out there. (Believe me.... some support on other casinos are horrible)