ITunes account not able to purchase apps?

I got a new iPhone for christmas, and I now can't use it to download anything from the app store, it says i have to confirm my payment information and I do that, I put in all my card details but it just says "Your payment method was invalid, please try another payment method". Has anyone experienced this before or have any solutions.

Also I have 10 pounds of store credit on my account from a gift card which I can't use either because it want's me to 'verify my payment information'.

You can't use prepaid or gift card you need active CREDIT CARD. Or BANK CARD

Yes this message arrives if your connection is not secure or your card is not applicable with iTunes store. In my country there are very few Credit/Debit Cards which work with iTunes Store. Most cards just don't work with it but work perfectly on other sites.