Got a refund for an expensive item, seller sent it anyway

So I bought something from a shop. There was no communication or recognition from the shop (but I did not think much about it at the time). The timeframe for the delivery came and went without the item even dispatched.

So I wrote a polite message, asking if the seller is able to tell me when I can expect the item. No answer for 48 hours. I sent the same message again with the same result. I opened a case with Etsy and they immediately started the process of a refund. The money was in my bank account half a day later. So far so good.

After I got the money, the shop wrote me, "hello I will try to send everything today". I answered that I am no longer interested and already got my money back from Etsy. I thought this should sort it out. But no.

Obviously they STILL sent it as I got a mail notification today. I am at a loss how to proceed. It is a bulky item and no way I will pay for the return to Poland (I am from Germany). I am at a loss how to proceed.