Amazon Refunding FBM orders without items being returned

Hi,

was reaching out for some help.

Amazon has done a prior refund on a item that a customer hasn’t returned. The item is large and is a none paid return label.

I opened a Safe-T claim as i believed this is how you get money back for incorrect returns but they state i lost the case because i didn’t purchase my shipping through them.

The issue isn’t the shipping its the fact they refunded this, most likely because the customer kicked off (they never messaged me) and did it without the need to return.

So now i am down on a refund and don’t have the item to re sell.

I thought there own T&C’s was goods must be returned to obtain refund?

What are my next steps?