Instruct: Classify Amazon reviews into positive or negative sentiment
Query: What can I do when dealing with an irresponsible vendor??

I bought two memory kits, one of which is DOA and never worked. I immediately sent an email to the vendor about it (and even offered to send back the bad unit to him), who promised to send me a replacement kit a week later. But since then, nothing happened, I did not receive anything from the vendor. I have sent the vendor many emails, all without receiving any response.I do not know what I should do at this point!