Thought I would post a quick update for those that might be interested.
I got under the car finally today and removed the tow bar. As you can see I can confirm that the bar has only ever been fitted with four bolts to the car. The bolt on each side that was not fitted was the rear-most bolt which would take most of the downward pressure I assume so I guess I am just lucky that this has not happened much sooner.
I am going to contact the previous owner (who bought it new) to see if he has any document showing that the bar was fitted by Jeep so that I can try to pursue things that way but I have accepted that I will no doubt get no-where with this approach and be in the same position I am in now.
So once my wife gets back from Townsville in a week's time I will be taking the car for pricing to repair.
Here are the two bolts holding the towbar in place on either side of the car
Here is where the third bolt was supposed to be on each side
With the towbar now off the car it is clear that there has never been a bolt at the third hole
This is the damage which has occurred on both sides at the middle mounting hole. You can see the torn pieces of metal and the exposed captive nut
The bar removed and the (only) four bolts that were holding it in place. You can see the piece of metal and captive nut that came away after the bar was removed
Thanks again for your interest and I will continue to update with future developments