Gosh, I know. Mistakes do happen but how you handle can make all the difference, huh?
Well... finally got my ponies today, and going against what I said above, I've left a neutral. There are rodent chew marks all up the neck and chin of one of the ponies which were not mentioned in the description or clear in the photos (which the seller advised the buyer to refer to for condition: 'what you see is what you get'. The one shot that did show that side of the pony was an upside down shot that revealed nothing other than the ink mark that they had at least had mentioned). Sigh. And leaving it at that. I could have contacted the seller about it before leaving the feedback, but in this case, I have had enough. Have no intention of having anything further to do with this seller, who appears to have disappointed three other buyers total now, based on the three negs they've now received (two of which either mention awful customer service or lack of communication, so looks like I wasn't the only one having trouble here).
Checked the tracking of the parcel that was sent to me in error, and according to that tracking, it is now with the correct buyer.