The last days I've been having this error message in my iPhone 4 app. I can play music in my PC with my Spotify account with no problems, but I can no longer use the app as I get the error message "Streaming is only available to Premium subscribers."
* The country set in your Spotify account profile must match the country where your card is registered. If you intend to use a payment method in another country, you can make this selection on your Subscription page (We can only accept payment from our launch countries).
* Your card should be enabled for e-commerce transactions (Verified by Visa/Mastercard securecard card).
* Your card must be open to be used for foreign purchases.
* There are some banks that require other security authentifications, the most common one being 3DSecure.