I would also be interested in this, as I am looking at moving to the North, and would need to get a car to commute to work and back.
Slick is my warrenty at risk becuse of petrol diesel issue i had few weeks ago?
As already mentioned, there shouldn't be an issue with warrenty as there was no significant damage done which caused you to claim. Should they ask why the fuel filter has been changed, just say for peace of mind.
They would have to do to pretty extreme lengths in order to prove anything otherwise, to the point of stripping the fuel system out and sending it for analysis.
RE: The ECU - I am not entirely sure how it would be logged, as the reason the engine would have stopped would be the lack of ignition. It would probably log a sudden engine stop, but nothing else as to my knowledge there is not a sensor capable of detecting what type of fuel it is using. (yes I realise there are knock sensors, but these measure ignition timing not fuel values)