Refusal to refund

During the second week of October 2025 I saw an advert on social media that this company(Japs Auto Solution) have an engine that I was looking for. I have to pay for it R21 000 that include handling and courier service. Invoice was provided to me and the receipt sent back. Tracking number details were sent for express drop shipping company that will be used by them to deliver the product. Later they inform me about another payment that I need to pay for RRIF insurance which is R12 500 which I told them they will have to pay it. They are refusing to refund me now as I don't want their engine anymore with all these delays.