Angry customer

I purchased Slim Harry Potter red flip flops on the 07.01.21 and they have become faulty and strip have came off. The item cost R450.00. I went to the store on the 09.04.21 and was advised that the item is non returnable because it is customer negligence. At the point of order I was advised item is returnable within the 6 months. We purchase expensive brand because it is good quality. What they did is false advertising and also I feel that Havaiana is aware that they selling poor quality shoes hence they giving their customer hussle to return or refund. I was given an email for customer service to complain still no response up to date. I'm am now sitting with R450 Flip flops that I can't even wear and is less than 6 months. How terrifying is that? I need help as I am not a very happy customer. We used mu boyfriend details to purchase and the number is *** and my number is ***