no refund or replacement after cashier mistake

On Saturday 11 April 2020 i bought a cliq electronic cigarette. The cashier gave me the wrong refill cartridges and when I wnt back today 14 April 2020 Thw manager on duty refused to refund or replace the wrong cartridge as i have already opened it to refil the elctronic cigarete. The managers argument was that no one would buy it now as it was already opened. I find this extremely poor customer service, as the cashiers sold me the wrong product to begin with.