Lessons to be learnt here: Not ok to automatically keep something if a mistake has been made (ended up not being an issue in this case). Gloating about a win when it's to the detriment of someone else always looks bad. Always best to contact people calmly without using conflict provoking words. Pays to never jump to conclusions when rational explanations can be made. Making decisions based on greed then criticizing the outcome later makes you appear mercurial. When everyone is saying you are the problem, it's often true.
as the seller, I sold a couple of brand new Apple Magic Keyboards. Both were unopened, still in the box.
Parcels were delivered in perfect conditions, but we had two different results
the first customer was 100% satisfied, for the product, and for the service
the second customer opened a dispute, for 30 euro of goods, and for the only reason that he must have destroyed the keyboard!
I asked a couple of pics, the parcel was delivered intact, and the keyboard was brand new: how could be so damaged?
was it defective? it might happen! There is no need to insult, and to call people "dishonest".
anyway, I promptly replied with a money back proposal for the good, and he insulted me again because he wanted 100% money back, including the shipping cost.
and so I did, 100% money back, but then I included this user in my eBay shop's blacklist.