No recourse for FBA sellers to stop fraudulent returns.

We keep getting fraudulent returns (a completely different item is returned while getting refunded by FBA). 5%-10% of our returns tend to be fraudulent. They get sent to our warehouse as unfulfillable, but by the time they reach us, we have no way of tracking which order was the fraudulent one since all of them get placed in a bulk shipment.

Why does Amazon have no recourse for FBA sellers to make a claim for those orders. They are killing our return rates without being marked as fraudulent.

Any help would begreatly appreciated!