If i bought a key from the private online shop is it still possible to get a refund? It actually makes no sense - what amount of money will they refund?
As far as I am aware you would only be able to claim a refund through your retailer - contact them for more information.
I very much doubt you'll get a refund from a private online shop ie CDKeys / GMG / Kinguin etc They have no way to prove / block your key. ONLY chance is if you paid via PayPal then you may be able to claim back...