What I would like is to be refund in credits. Apparently it's possible if I ask for it. This is what I will do.
The Team will decide this on a Case by Case basis.
In General.
If you still have the Animation Files, and you can still play the card.
There would be no Case to get a refund, just because you want one.
It would be similar to
I played the Friday Event and won 10 cards I don't want, can I get refunded?
If you lost the animation files and can no Longer play the card.
Then the Team might decide differently.
Normally your purchase history is used to determine the credits spent for the card
and that is what you would be refunded.
If you Won the cards in an Event.
then the Team would have to decide how to handle that.