Bad customer service

Purchased a pair of CROCS on Black Friday thinking the same discount online is applicable in store. Apparently the shop is not affiliated to CROCS SA. Shoes was R1000 and marked down to R800. I thought it was discounted to R550. ( the discount was not advertised in store either) I paid cash and only realised much later that I was charged R800. Store refuses to refund me. The store policy is that there are no refunds under any circumstances.