I had the same issue. I tweeted them and they fixed it in like 2 mins. You can also call them in need. Twitter was much quicker and more effective for me. Done within an hour of tweeting them. Its a known problem.
What you can also try is going to http://connect.dstv.com in a browser, logging in, and then checking if your dstv smart card is properly linked or even try de-link it and adding it again.