Assuming this is the one you're talking about....
http://www.ebay.com/itm/1994-Topps-B...p2047675.l2557
Sure the photo's aren't great, BUT without a doubt I can see the corner damage you're talking about. The bottom right corner looks horrible, the top right not so hot itself(but not awful), the 2 left corners look decent. Don't be mad at me here, BUT given how fairly obvious the damages are in the photos, I might side with the seller here. Forget about his stating "great condition", you had the photos to make that judgement yourself.
Now I don't know if you made the purchase on your phone or computer. So I'm just throwing this out there blindly. I can understand missing the damage if you maybe made the purchase using your phone where you didn't get a great view, BUT if you're making a purchase of that price, or on a card claimed to be this rare, you should probably make sure you get the best possible view you can on your computer.. And looking from my comp, the damage, again, is obvious..
I don't envy your situation. But I completely get where the seller's coming from here. I wouldn't offer a partial either in this case, because the condition was clearly evident in the photos...