I will open a separate post in respect of the problem that necessitated calling Porsche Assist.
My initial call to Porsche Assist was answered promptly and they dispatched an AA breakdown van which arrived on time. Unfortunately the AA Technician was unable to resolve the problem and the vehicle was recovered on an AA flat bed to my local Dealership. So far so good.
Porsche Assist advised that Enterprise would contact me to arrange a replacement vehicle. Enterprise claimed that their process was to drive me their Branch and collect the replacement car from this location. This was not convenient and after escalating the issue to Porsche Assist, Enterprise grudgingly agreed to deliver the replacement vehicle to me. My Dealership advised their understanding of the process was for the replacement vehicle to be delivered to a location that was convenient to me NOT Enterprise.
The replacement vehicle (Mercedes C Class) was eventually delivered, clean but with only a quarter tank of petrol and an empty washer bottle. Not what I would have expected from a mainstream vehicle rental company.
On the advice of my Dealership I will be writing to Porsche GB seeking clarification of the replacement vehicle process.