Intermittent engine hesitation / misfiring problems since 2011, causing actual breakdown only once sometimes causing EPC light to flicker. Dealer has investigated over total of 10 weeks but still not have identified actual cause. Compression tested, changed spark plugs - (2 were brown/2 were white?), reloaded software. In Sept took fuel sample, contains 0.4% water, all else clear. Without knowing what fault is, dealer saying this is cause and saying liability is mine.