Even if you only want something that is free, Apple may insist any problems it may be having verifying an existing payment method first be resolved with your with your financial institution. You can try removing payment information (see the last two links) to avoid the problem with the existing method but other topics suggest if you have any payment form currently on record it must first be verified before you can change payment type.
On a mobile device go to Settings > iTunes & App Store > Apple ID and check your payment information is current.
Add a payment method to your Apple ID - Apple Support
- Are you (still) using a valid payment method? --> Payment methods that you can use with your Apple ID - Payment methods that you can use with your Apple ID - Apple Support (Discussions on this forum mention problems with some debit cards, and pre-paid "credit" cards.)
- If your payment method is declined in the App Store or iTunes Store - If your payment method is declined in the App Store or iTunes Store - Apple Support - various reasons why payment method is declined including pending purchases.
- If this abruptly started happening try removing and re-entering your payment information -
Add a payment method to your Apple ID - Apple Support
Remove a payment method from your Apple ID - Apple Support
- Do the name, address (all spelling, letter case and punctuation), and card numbers exactly match those you have entered? You didn't mis-type anything?
- You entered the 3 digit CVV security code for the card? Correctly?
- The country for the bank and your address are the same as the iTunes Store country you are using?
- See the end of the document linked above for special measures that may be necessary for some cards, plus about contacting your financial institution to make sure your records match.
If you still have a problem contact Apple:
Click here --> Choose your country or region - Official Apple Support Select your country, then a product.