Ardene Peek-a-Boo Dress Size Medium but Fits SMALL

I apologize for the lousy picture. It is dark denim color but not actual denim. It has studs at the color as you can see, openings on the sides. It is a size Medium on the tag but it runs smaller, more like a Small. I bought this for my teenage daughter but I never saw it in it, so it may not have been worn. The color is between a denim blue and a gray but I think it pull more towards the gray