H&M Store Mix-up - Gender-Sized White T-Shirts in My Purchase

Even though I purchased two white t-shirts from the H&M store, I received one in men's size M and the other in women's size S. I find it quite puzzling that one item is women's size S and the other is men's size M. It would make more sense if they were both men's size S, but this mix-up is truly baffling. I contacted customer service to express my concern and noted that I had bought them at a reduced price. Regardless of my attempts to buy them again, they insisted it was not their responsibility since they were out of stock and the price had gone up. They brushed me off, telling me I could voice my grievances wherever I pleased.