Slazenger.com Shoe Size Discrepancy

After wearing the two pairs of shoes I bought from Slazenger.com's 'buy one, get one free' promotion, I couldn't help but notice that their molds were different, even though they were both size 41. I asked for an exchange or refund but was told that since the product had been used, I couldn't get either. I used to think Slazenger was a trustworthy company, but it turns out I was wrong. At first, I didn't notice the glue marks on the shoes. However, as they began to cause discomfort to my feet, I decided I wanted to exchange them. Regrettably, I didn't receive any help with this issue.