You subscribed to a paid service but you can't get the free part of it. How lame. I'm sorry, but they don't deserve to have your money anymore. You should ask for a refund.
I'm not trying to pick on Slashdot here. I'm being fair. Even if there is a technical problem, you owe it to your customers to be direct and accommodating about it. I know this is an isolated incident, but this is no way to run a business. It's completely unacceptable and unprofessional.