Why not continue with your sociology and either RE or english? That way you might get atleast a D in your other, ontop of your sociology.
I'm always of the mindset that any A levels trump none. But if you're planning to go to uni, I'm not sure. Perhaps, like I said, continue with sociology and one other this year. Then next year finish your A2 sociology and your other subject. Year after, perhaps be an extenal student and either resat any modules from your two subjects you didnt do well in and perhaps pick an AS up that catches your eye?
What are you hoping to do at uni?