Bad quality

I bought a summer dress during their autumn sale in the middle of March (style no S17 ********** PGO1047). I never used this dress until spring - September month. I have only worn the dress 3 times. The dress is torn in between the stitches. It’s not the question of the dress being small, as it’s a free flowing dress with 2 layers, both layers are torn. I took the dress to the shop and I was informed that because I purchased it over 6 months they cannot assist me. If they do not send the dress back to the supplier how is the supplier going to be aware of their mistake. I am quite aware that the dress was made in China but that does not mean that they have to sell us inferior quality. Although the garment was made in China but I was expecting the best quality as they should have done the quality assurance. Also taking into consideration that Queenspark it’s a boutique and their merchandise does not come cheap. All the clothes that I bought from Queenspark Southgate 5-6 years ago they are still in good shape. However a dress that I bought over eight months it’s already showing distress, that proves that they no longer sell quality clothes.