There is a difference between online shopping using your VISA debit card/credit card and Internet banking facility on your account. You may very well have Internet banking facility, but restricted ability to shop online using your VISA debit/credit card. In order to be sure, verify this from your bank.
If your country is listed in the iTunes store and you are using a valid VISA debit/credit issued from the bank of the same country with a verified billing address, I see no reason why you should not be able to make purchase, except where your bank is declining to authorize that transaction.