In their defense, I can understand when they don't have the room for some items. They would know what does and doesn't sell, and what they have an overstock of. And they aren't the only charity that has refused items from time to time. Even the food bank will tell you not to donate what they have too much of already.
Maybe try a smaller charity, like a local women's shelter, who may be able to use those items directly (either in the shelter, or to help women set up new lives), rather than selling them through a thrift store.