Even though this fortunately happens only very rarely, it sometimes does happen that the payment total for a card payment is frozen on the payer's bank card, but a timeout or some other unexpected issue causes the payment process to fail.
Barion reverses such payments, and the card-issuing bank is required to release the blocked payment funds. The release usually goes through within 24 hours, but depending on the specific bank's terms, and whether the failed payment was of the immediate, delayed capture or reservation type, the process may take up to 7 or even 21 days.
Regrettably, during this time, the cardholder can't access the money involved in the authorized but later reversed payment.