Are you guys trying to buy on a foreign PSN.
Because if it is the case, you can forget it, SONY's policy is to prevent anyone from shopping on a foreign PSN (the PSN you can shop in depends on the country that your credit card bank is settled in).
So to make it short ... if your credit card is from a British bank, you can only shop on the British PSN.
Of course it is not automatic, that is why so many of use could shop abroad without problems, but it seems that Sony is checking every PSN account to make it up to its policy.
That is an outrageaous policy, completely consumers'unfriendly.
F**k it.