Petrova worked as a cashier at a bank currency exchange

Petrova worked as a cashier at a bank currency exchange office, and an agreement on full material liability was concluded with her. When exchanging foreign currency, the client deceived 7 thousand US dollars from Petrova. Petrova’s attempt with the security guard to detain the client was unsuccessful.
Petrova reached a written agreement with the bank´s management that she voluntarily indemnifies half of the material damage caused through her fault, and the bank refuses to recover the rest of the money. In accordance with the agreement, Petrova contributed 3.5 thousand US dollars to the bank’s cash desk, however, the employer filed a lawsuit in court to recover the rest of the damage.
Petrova at the hearing asked the court to refuse to satisfy the claims, citing the fact that the labor dispute is an unresolved disagreement between the employee and the employer, while a written agreement was reached between the parties to the dispute. The court, reducing the amount of damage, nevertheless recovered from Petrova 1,5 thousand US dollars.
Is the court decision legal?