workshop stumped by my rangie

my 03 plate range rover vogue has broken down for the second time in as many weeks, first time with the wife she had left it for 10 mins went back to it but it failed to start so was taken to garage and diagnosed with no 1 and no 2 injectors failing so were replaced .got it back last thursday then last saturday in cornwall (i live in norfolk) it broke down again. it got taken back to the garage were the computer diagnosed the high pressure fuel sensor so that was replaced but still fails to start . the workshop are now stumped and dont now what to do next.
we had a tow bar and electrics fitted about 3-4 weeks ago using the plug in electric pack from landrover , someone has now told me that if it wasnt set up by landrover this could be sending wrong info to the ecu giving the reason for non start.
anybody got any ideas
cheers

surely with that information given to you about the tow pack when they do a diagnostics check shouldnt this be picked up as a reading .only a suggestion or its some info to give the garage to check

If the engine is fully mobilised,cranking but wont start,it is either low,low side fuel pressure,(low side pump/s) faulty pressure reg,Faulty high pressure pump or my money would be on excessive leak by in one of the injectors.

Spoke to the local Land Rover dealer this morning and apparently land rover have not heard of the tow pack doing this ( i think someone fed me some duff info)

OK
been to see the garage this afternoon and they showed me what they think is the problem .
A valve on the side of the pump (i think thats what he said) which has 2 very very small washer/seals on it has been pulling in air, 1 of the tiny washers had split and the other had perished completly so hopfully by the end of the week we shall have here back and they can have there god awfull VW Passat back.

lol good luck

OH YEAAHHH
I got my rangie back tonight and she drives like a new car thanks to 2 little peasy o rings costing £5 (still got the expensive bit fitted as well) .
Does any body know if i can fit the 06 model headlights and grill to my 03 td6 if so where is the best place to get them and a supercharged grill from
CHEERS