I want my Money Back

At Shoprite Bridgecity, I used my giftcard to pay and they said it is decling so since giftcards dont report I took their word for it. I then used my cash to pay... so When I get home and check the balance of my card under www.whatsonmycard.com and it shows that Shoprite took R140 from my card

I went back to the Store about this and they're saying theres nothing I can do about this.

I want my money back!!