You can be banned from Socom but I have never actualy seen it happen. If someone (a jurk) went around taking info then sending it to sony telling your glitching and giving your name and time ect how could they ban you there is no hard evidence that you cheated its one mans word against another.
For your connection problem, buy a new cable and try that. When I first got my online set up I wrecked the prongs on the cable trying to pull it through holes in the house

So check to make sure your prongs on each end of your cable are straight and not all messed up.