Substandard goods at plastic depo

I bought a Deluxe folding drying rack on the 16th of August. Product is substandard and is breaking. I then brought it back to the shop, unfortunately I had lost my slip but the manger was able to retrieve my sale on the system using my banking details. I'm now in the shop and struggling to reach a compromise with management all the drying racks are dented!!!!!!!!!! There products are substandard. I was told there nothing she can do for me because I didn't have a slip and that the slip on the system was there's and not mine. I just want my money back or a product thats not dented.