Victoria secret recently had buy one get one free on a selection of bras. I bought them online and I'm in the UK so I can't return to a store. One of them, the one that was free is too big but the smallest size they sell (I'm very flat chested)

So can I return it and ask for an exchange for a different bra from the offer? Or if I return it will I just get nothing back because it was free? Or just what would happen?