Engen garage Jules street

On the 28th of December 2020 I bought a motorcycle, I stopped by that garage to buy two bottles of oil but not knowing much about motorcycles I bought a wrong type of oil. After two days I went back asking for a refund, the cashier told me they do not do refunds she took back the bottles of oil from me and said once they sell them I would be able to get my refund.

I called Engen in Sandton and the the manager told me it wasn't ethical. At this moment I am feeling ****** and having second thoughts about Engen garages.