billing methond problem

Do you mean that the card is being declined ? Do you have another card that you could try, preferably a credit card ? Debit cards seem to be being accepted less-and-less by iTunes.

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).