Cashier advice costs me R499

I bought a Safeway plug in fan heater for R499 on 9 June from Hillcrest Clicks. I didn't have my Clicks Club card with me. The lady next to me offered that I use hers, I ignored. Then the cashier Hope asked me if I don't want to use the ladies card. I didn't think much of it. Now the heater is not heating up my small student room and it makes a huge noise I went back to the store which doesn't have any other heater (that I prefer) to replace with and is refusing to give my money back even if I have proof of payment and original packing due to me not having the Clicks Club Card the cashier offered me. Now I am sitting with heater that is not working and R499 less. And Clicks is just saying their policy says no using of other peoples cards YET I ignored the request and THEIR cashier convinced me to use it