I have been vey pleased with what I've ordered from Cupshe, even though the swimsuit I really want does not exist; one piece, colourful, simple straps and very deep scoop back almost to, but not quite down to tip of bum.
Unless my recollection is wrong, I think when I contacted them they sent me a print off label link for returns.
Sadly, I think some of the charged returns that seem to be around now are because people went to far. For example ordering 20 dresses and returning 19.