Are you sure it's a new development? They are supposed to lean slightly to the right (assuming it's a LHD car and you are checking without a driver). The factory actually modified the rear springs so the car would sit level with only a driver.
If it is a new development, I would not suggest a "quick fix". I've had several broken rear springs; which after all are all that hold the rear axle to the rest of the car.
But you could remove the factory spacers from the RH rear spring (which will raise the suspension slightly), or add an extra pad or two to the RH front spring. Neither one is exactly a quick fix though, there is some work involved.