I read your “OP” as “original poster” and thought you were saying he did it himself haha. Oops.I would not trust Optics Planet to offer you a decent remedy. I would contact March directly and negotiate for a new UNBLEMISHED item from their inventory. That is embarrassing for them and I wouldn't be at all surprised to learn that OP had something to do with it.
That said, 10% off for a minor cosmetic blemish is pretty good — especially if the scope is going to be used hunting a lot. I would request Optics Planet give me $300 cash and not store credit, though.