What should I do after receiving damaged furniture post-payment?

I purchased furniture from a shop. Before making the payment, the seller was polite and cooperative. However, after receiving full payment, his attitude changed completely. He delivered old, unfinished furniture with rusted metal parts, despite our clear request for new items. When we raised our concerns, he initially agreed to replace the furniture, but since then, he has stopped responding to our calls and has not taken any action.