Sorry to hear that. It's relatively rare for a spark plug's ceramic core to fail and fall into the cylinder but it does happen, and will cause the damage you report. Peugeot's 1.2 3-cylinder turbo motor is apparently prone to similar plug failure and engine damage.

Is the car actually out of the warranty period? If it still has warranty remaining I would play merry hell with them, a spark plug is a service item but NOT a 'wear and tear' item like a clutch, brake pads or tyres. The plug should last between scheduled services, and assuming that you have stuck to the recommended service intervals then I would think you have grounds to fight to get this covered, at least in part.

Many thanks for your comments.

Still hoping to turn this around. But in this day and age, spark plugs should be redesigned if it is possible for them to wreck engines.

The spark plugs were in good condition and not due to be replaced at last service. The argument is whether a spark plug is a consumable or component, which apparently invalidates the warranty.

The spark plugs were in good condition and not due to be replaced at last service. The argument is whether a spark plug is a consumable or component, which apparently invalidates the warranty.

That is an argument Boris might be proud of. Spark plugs do not get 'consumed' - at least they should not, in the way yours has.

It is a disingenuous and fallacious argument attempting to introduce a false distinction. A spark plug is of course both a component of a petrol engine and a consumable, in as much as it needs to be replaced as per the service schedule, timed to be well before it either performs badly or wears out.