I've just bought xenon headlights for my C4, am I correct in saying this should be a simple plug and play, I notice the xenon lights have a pin connector on the lights for connecting into the existing loom as per the original lights but they also have a pin connector on the metal box (is this the driver ?) what should plug into this, do I need to buy something else or is this connection already on the car. I can't check the car just now as it's not with me