According to the law, there is no stipulation that the deposit is not refundable. As long as the circumstances stipulated by law are met, the party paying the deposit does not perform the agreed debts and has no right to demand the return of the deposit.

The relevant laws stipulate the Guarantee Law of People's Republic of China (PRC).

Article 89 The parties may agree that one party shall pay a deposit to the other party as security for the creditor's rights. After the debtor performs the debt, the deposit shall be used as the price or recovered. If the party paying the deposit fails to perform the agreed debt, it has no right to demand the return of the deposit; If the party receiving the deposit fails to perform the agreed debt, it shall return the deposit twice.

Article 90 The deposit shall be agreed in writing. The parties shall stipulate the time limit for the payment of the deposit in the deposit contract. The deposit contract shall take effect from the date when the deposit is actually paid.

Article 91 The amount of the deposit shall be agreed by the parties, but it shall not exceed 20% of the subject matter of the main contract.

To sum up, the other party can only charge you a deposit of 900, and you have the right to get the rest 1600.

If necessary, welcome to consult!