Me too....well Morrisons......never had a problem.....have filled my vehicles up at asda for the last 15 years only once I had water in the diesel filter
Have you put petrol in?
"Just the jet station is right by my house and never busy."
and that's probably your problem, if it's not busy it's not turning over fuel and it's been sitting, potentially a lot of water / impurities in it. Always better going to places that have a decent turn over
Considering the high state of tune of the 300tdi, I'm surprised you dare run it on anything that has not been blessed by the pope himself!
In seriousness, being a landrover, it's far more likley that somthing else has just broken instead.