That's the main change. On the old wiring, the battery had its own charging line on pin 2. On the new wiring, the battery is charged from pin 4, BUT the charging is switched on and off via a relay in the caravan which is powered by pin 6 (the fridge.)
So you definitely still need the relay in the fridge circuit.
I can believe full well that the Renault instructions are talking
. From what I recall, the instructions with the official wiring kit for the Lag II were the same. In the end, the only part of the 12S wiring that I used from the kit was the socket. It's not uncommon for car manufacturers and dealers to be clueless about towbar wiring. I know it's too late for you now, but I'd always go to a towbar specialist rather than a dealer. They'll generally do a better job, and they tend to be cheaper too.
It's a great idea checking once you've got the caravan, but how are you going to know? On most modern caravans, they seem to have done away with the good old 12v lamp on the front of the fridge to show you've got power from the car. The first you'll know about it is when you leave the caravan hitched up for too long and you can't start the car because it has a flat battery.
If your caravan doesn't have a 12v indicator on the fridge, you'll have to use a multimeter to measure the voltage of the car's electrical system and then try switching the fridge on and off. If the fridge really isn't drawing any power, the voltage shouldn't change when you operate the switch.
In your shoes, I think I'd just buy one of these and fit it myself.
Towsure â***8364;***8220; Towbars, Camping and Caravan Equipment - Product Details
Better that than finding yourself stuck at a motorway service area with a flat battery. It does mean that they've won though. What's more, if they've made a hash of the wiring (and I wouldn't be surprised since they seem to know so little about it) then they can probably blame you for any other faults once you've modified it