The online page for this item claims it is 100% cotton. When I received the item, it contained 4 gray (heather) pairs of underwear, and one black pair. Although the black pair is 100% cotton, the gray pairs are 75% cotton, 25% polyester, and much warmer than the cotton ones. In fact, the gray ones are too warm for summer use. Regardless, I am miffed at the false advertising. I would not have bought the item if I had known I was buying a cotton-poly blend. How do I return this for my money back?