Feedback on eBay is a very particular term. It refers to the number of posted remarks after your name from those you have had transactions with.
This seller did not leave you inappropriate 'feedback". He may have been rude and insulting, but of course we can't see what messages you sent to him. As far as the general eBay population is concerned, nothing is happening. Your communications are private.
Or were until you posted your upset here.
What can you do? Not much.
You can add a Response to the feedback you left for him and also to the feedback he left for you. Keep in mind that the most effective feedback is calm and factual. 'Broke down after 4th use. Seller uncooperative and rude.' for example.
If the item has a warranty, you can try going to the manufacturer directly. This is how most product failures are handled. You may have to ship the broken item to the manufacturer (or possibly importer) for repair or replacement.
