Two weeks ago, I came across another iPhone 6 with the random shutdown problem, however this has a serial number which is outside the ones identified by Apple (How to identify iPhone 6s under battery replacement program) which made it not eligible for the free battery replacement.
Today, I’ve found out the battery shutdown problem is ‘more widespread than thought’. Reported by 9to5Mac, it appears the shutdown problem is affecting iPhones outside the affected batch.
If you have a iPhone 6/6s which is exhibiting the problem, email Apple, Facebook Apple, do whatever you can to make them be aware and get it repaired. Consumers should not be sold phones which works just ‘most of the time’!