Card declined

It's possibly being declined because it's a debit card, not all seem to still be accepted by iTunes, and they might no longer be accepted at all in some countries. Do you have another card that you could try, preferably a credit card ?

For a card to have a chance of being accepted it needs to be registered to the same name and address (including format and spacing etc) that you have on your iTunes account, and have been issued by a bank in the country where you are (and therefore the country which is on your iTunes account).