Gucci Ballet Flats new in box size 37.5

Super cute Gucci patent leather ballet flats brand new in box with receipt (bought from the website The Real Real) they are unfortunately too big for me and I can't return them. Gucci size 37.5. I usually wear a 7-7.5 and these slip of if I try to walk in them do I would say they are better for someone a size 7.5-8. Only tried on inside! These are brand new and authentic. Wear to work or out on the town!