I'd contact the card issuer at the number that can be found on the back of the card and explain this to them. They are much better at explaining their refund and transaction cancellation policies and how much time is required before the money is reloaded back to the card.
You should also be able to find these policies in the user agreement that should be found on their website.
If it were me, and I really wanted the coin, I'd user another payment method to get the transaction completed on
ebay ASAP.
Good luck!