Sandgrens Brett low NIB

Brand new, never worn Sandgrens, still in the box with all the papers and receipt. My mom just gave me these for Xmas, but I have to size up to 41, these are size 40. Since she bought them more than 30 days ago, they won’t let me exchange them even though they haven’t left the box and I have the receipt. 😢 they fit like a 8.5 or 9 in my opinion.