Hydra never had a legal right to hold your deposit. They tried this with many people but as they simply had not fulfilled their part of the agreement, they had no legal basis to hold on to your money.
In order to break a contract and retain a deposit like that, they have to get a court order. They weren't and still aren't in any position to convince a court that they have upheld their part of the contract, that you haven't, and that they should get to keep your money.
You can still get your money back if you take them to court...but you have to decide if the cost justifies the return.