In my experience with this issue, a garage will go as far as plugging an OBD / fault reader in, and if that doesn't show an issue, they won't look any further. I had two garages do this, even when I told them I suspected the spark plugs to be the issue, based on these forum threads. When I spoke to a main dealer, describing symptoms and my suspected cause, they said it couldn't possibly be that, and wanted me to get a full clutch replacement for about £4000. Realistically, if you're taking the spark plugs out to inspect them, it's probably easier to put new ones in than the originals. They might be hesitant to do so without good cause. I'll be honest I'm still not completely certain why the sparks, leading to an intermittent misfire ends up causing issues with the ESC, but hey. I can see why garages are sceptical to just replace them if they're within life expectancy. If you can't remember when you last had sparks (and or leads) changed. Or if they were over 10,000 miles / maybe 2 years ago, it's probably fair to get them replaced, they're not too expensive. I'd be surprised if a garage charged more than about £200 for parts and labour, and worst case you've only replaced a maintenance part a bit sooner than necessary. Mine showed some signs of corrosion, presumably from water getting in the seal around the coils, so even if the car has been sat, they could be a little worse for wear. The symptoms sound very similar to my issue, resolved as above. But I'm aware describing snatching, juddering and skipping is all very vague and quite hard to check if we mean the same feeling. My OBD only showed an error when the EPC light was on. As soon as I turned the car off for a while and let the EPC light go off, the OBD didn't show a code anymore. I'll also add, I separately was running an experiment running both E95 and E99 for prolonged periods (3 months alternating periods, about 4000 miles a pop) to check fuel economy, and found it made absolutely zero difference to the symptoms while I had this. In terms of safety, on the two occasions the EPC light came on, I just drove it home / to the next services and no further before turning off, letting it reset and carrying on, albeit cautiously with the accelerator. I don't think it'll be fatal, but you definitely lose all ability to accelerate, which was not ideal.