Refused exchanged on starter by the rude Kady at the door

Drove my car there go figure starter as it was ******, give the starter that doesn't fit, I took it back the security recognize the marking on the box ,also the sales oerson knows the lady refused to authorize the exchange because I lost the slip even if she has other proof the item is from their store I asked for manager she refused I asked fir duplicate slip and cctv she refused everybody sisnt know how to help because she's refusing saying if she doesn't want there's nothing they can do to help me xchamfd the item I know the shop has stock taking measures but she said no. I don't have money as I am receiving sassa , the starter took all the money now I have to wait fir sassa to buy another one what must I do with this one. It wasn't even 12 hrs that I bought and asked for exchange not refund.