Poor quality

I bought a pair of pumps and had it one for a couple hours cause i realized that as i was walking in the street...the stitching came loose ..u can clearly see its was poor stitching..i took it back to the shop where i was shown the refund policy...and was told by the manager that unfortunetly ...they cant accept it as i had worn it already and i had to check the shoes first before wearing it ..OMW ..pls tell me how.many people check there shoes before wearing it...it was not even my fault but clearly a manufactures fault....