Returning the sneaker for the right size

I bought a superga sneaker I love that sneaker but now the size is big, and I returned the sneaker to get the smaller size but now the ladies that work there are telling me that they can't take it it's going to be a long prosses of writing the email. It's the first I hear of such cause when you buy something and the size it's not right you return it without a Hassel. I'm not requesting for the refund. I'm so disappointed...