Brand New Black Corset Top with Zipper Back

Brand new, never worn. Got this from an online retailer and the size was completely wrong, but the seller refused to refund it. Material feels like nylon with some strech. I am 5'2" 118 lbs, generally wear size 4-6, and have a chest size of 33.5", and this corset was too small for me despite being advertised as a medium. I was able to get the zipper only halfway up. Please check the photos carefully to figure out sizing. Please feel free to ask if more photos and measurements are needed.