Amazon Seller Returns Issue

The Amazon Seller Fullfullex returns are flawed. We have customers submitting returns for any reason possible even after 30 days and we close the request and a few days later Amazon randomly still refunds the buyer with no proof of return shipment or anything. How is this legal!? This is fright robbery and Amazon seller support is completely useless and the disregard for sellers is absolutely disgusting. They keep saying open a T-Safe claim but it gives us an error when we open it and we keep explaining this and we get the same scripted responses! Can anyone help with this situation? We are now out almost 1k for no reason at all. When you close a return why would the system do this days later. We closed it on September 29 as the reason as “Customer Cancelled return request” and on October 3rd a random full refund was issued to the customer!..