It is easy for you to negotiate with them again and secretly record the negotiation process. It's a recording, so much the better if it's a video. Although there are no invoices and receipts, we can take this negotiation process as evidence and pay attention to negotiation skills. First of all, you can confirm that you bought it here. It can be said that suggestive questions such as "the ring I bought here is not platinum" can be complained to the administrative department for industry and commerce. When the industry and commerce come to check, they will check his goods and serial numbers, as long as they match yours. Or they can sue directly, and the legal fees will only cost 50 yuan. Just spend 50 yuan to play, which is enough for the seller to toss. If the case wins, you have to get 50 yuan.