So following my vehicle being recovered on Thursday to SMC Aldershot, they were able to repeatedly stop and restart the engine with no faults.
They contacted the upper echelons of Cupra/SEAT who requested that they send over all diagnostics and information for their review before trying anything that might muddy the waters.
This is clearly of great concern so hopefully gets prioritised - although I’m cynical that they will reach a resolution quickly... for the time being, I’m stuck with the Mitsubishi PHEV which in all fairness isn’t a bad vehicle, although clearly down on power and lacking in any driver involvement!
I truly hope your case being the most extreme of the faults we've seen son far, help shed light on the big issues on the car, and it gets fixed soon enough.
I think the worst part for you must be driving the PHEV haha