Part of the risk you run when selling on ebay.
If you were unlucky enough to get a bad buyer, they would open not received cases for the other two items and you would have no choice but to refund.
Bit of a pain but we always recommend with buyers agreement, to cancel sales and relist as one item for buyer to buy again. Cancellation automatically refunds the original payment.
Long winded I am afraid, but it is wise to understand the risks involved.