Paul

Where abouts in the UK are you? there is an experienced independent in Derbyshire that may be able to help. Also very experienced dealer in south Lincs.

Has your mate spoke to Isuzu customer service, sound like un acceptable treatment from dealer.

try a search, on here + on web, think there was mention of a good Isuzu forum.

I am no expert on these, but 2 non runners I have fixed have been a) throttle plate stuck shut 2) oil pick up broken on injection oil pump feed ( not main engine oil feed)

Cheers Aidan