Well I have found the 'fault' on the fog light problem.
and it was a bit of trial and error, a volt meter and a 12 volt 'tester' lamp that assisted me !.
I had kept the old non-fog light rear cluster looms, and after giving them the once over against the 'new' fog light cluster looms, it was strange to see that the earth (brown) cable was interchanged with the fog light (grey/white) in the six-way connector in the rear of the car. The older non-fog loom didn't have the grey/white cable obviously !, but the positions of these two wires were 'reversed' in the six way connector.
It couldn't be that obvious could it???, Well after confirming what colour wire did what, with the help of a volt meter and test lamp Yep!, they were !, so a quick switch around and solder and shrink wrap, the lights on the rear of the car work as Porsche intended.
If anyone wants to do the job, you will need the switch for the rear fogs, (The loom is there behind the dashboard, next to the front fog switch)
And the part number for the rear light cluster harness with integrated fog lights is 951 631 234 00
The wires are Identified as
GREY= (Two of them attached as one) Side lights.
BLACK= Indicators
RED/BLACK= Brake lights
BLUE/BLACK= Reversing Lights
BROWN = Earth
GREY/WHITE= Rear Fog lights
Having the earth and fog lights signal wires reversed, was giving me the wild light show, that had caused all the grief, switching on the rear fogs effectively put the whole cluster in series across the lamp filaments, and gave the weird results, but I wonder why Porsche 'moved' the earth cable on the fog included looms? another mystery!