If the diesel pump seized due to lack of lubricity in the fuel, then that
could snap the timing chain or timing belt of any diesel engine and is a separate problem from the original one of chains wearing prematurely. I can't see how Nissan can be held to account for misfuelling with petrol or getting a bad fill of diesel with inadequate lubricity. Maintaining a turbo diesel engine is no secret. Change the lube oil frequently. Either use only BP Ultimate diesel or use Millers diesel additive to give better lubricity to diesel fuel (www.millersoils.co.uk) Never switch off a red hot turbo, which it will be after running on the motorway, running up a long incline or towing. Always idle the engine for a minute or two to cool the turbo by engine oil circulating through its bearings