Your account was locked for multi-accounting amongst other reasons. Support sent you an email requesting that you verify documents. No response on your side to that email.
Can you provide info on how you came to the conclusion of multi accounting please? This just is not good enough, casinos keep doing this, we need concrete proofs of a misdemeanour by the OP or a flag could be in place.
OP should send or representative can do that also, so we'll know what evidence Stake.com has to prove that OP is using alt accounts when playing, this has been the case on so many accounts complaining for getting their account ban, they need valid proofs and evidence to justify this.