3) They blocked my wallet (with a large, amount of btc) !
Scam or no scam, that's the major mistake. Storing a LARGE amount of bitcoins on a wallet which someone else controls. You should keep your coins in a wallet which are under your sole and exclusive control. This means you and you alone know and have access to the private keys.
1) I send Btc from my account Litebit.eu, Btc come back - back! How, I correctly return Btc???
Didn't quite understand that part. I know you're probably in panic mode when you wrote this which explains the way you wrote this. Did you send back the requested bitcoins? If you refunded them the bitcoins, let them know so they can unblock the rest of your coins. The account block was probably done to prevent you from emptying the account while that transaction error remains unresolved.
If the withdrawal was really executed twice, refund them the second transaction and let them know.
Sounds weird though. Why can't they simply deduct the wrongly executed 2nd transaction from your (rather large btc) balance, instead of freezing the entire balance?
