Faulty Shoes

in December i bought two pairs of Kelso high heels, both the shoes are wobbly and uncomfortable. i tried to return them to Edgars Centurion Mall but was told because i didn't have the invoice the store couldn't accept them. I still have the boxes with the price on them, and i find this unfair. You can clearly see the shoes were worn once, but i will never be able to wear them due to the poor quality.