I'm sorry you got stung on this, but it's fine if you can just send it back to the retailer.
I don't use 50mm very often and hadn't acquired a 55mm f1.8. But I did want an AF 50 with a wider aperture than my Tri-Elmar, so I planned to get this one. And then after reading about itse weak AF I took the plunge for a used 55 1.8.
Despite your disappointment I love the picture of the woman in black – street photography in a dreamy misty pictorial style! Are you sure you don't want to make more like this?
Kirk