A monthly fee is charged for using a Visa payment card. It is deducted from the card account. If the balance on the card account is insufficient, the fee is deducted from your main account. If the balance on the main account is also insufficient, an indebtedness is accumulated and the missing amount will be deducted as soon as you add funds to the card/main account.
A single monthly fee is applied for multiple cards linked to the same Visa card account.
Information about all fees can be found here.