How can i get refund from the seller who has sold faulty item and refused to refund!

Seller “ZiniSoft” is sold a react native mobile app which integrated wordpress API. but the App is fully incompatible with All the wordpress theme otherthan they have used in that demo project. Also so much of bugs for both android and ios. i would like codecanyon to help me get the refund from them. I have been contacting the seller for refund. They simply refusing with their un professional refund policy which lead me to think that anyone can sell anything they wanted in CodeCanyon?.

Does anyone has idea or support how can i get the refund if seller refused?