This rear jacking point confuses me too. Looking under my car I have three nuts and bolts holding the rear valance. Then I have a metal cross member in front of the screws about 2 inches wide across the car. Where do you put the jack? On the metal bit or on the plastic where the three screws go through to fix the valance?
A pic would be good if someone who knows can clarify where the jack should go and locate the exact point of the cross member.