Thanks for the reply.
The offer is active for 18 more days. I don't have any other card or alternative payment method available. I've tried making a payment using 2 different networks (LAN and wireless) and 2 different devices (desktop and mobile) with 2 different browsers, even after clearing cache and cookies. All I receive is this message - all the payment details are correct and my card has international payment activated and is not blocked in any way. It would be a shame if I can't start my membership, I really wanted to use the service, especially with this price...