with it being an intermittant fault, you need to just keep driving about continuously datalogging the lpfp and hpfp.
I paid for a hpfp for no reason whatsoever. bear in mind theyre both ~£160 mark.
The garage wont know whether its the lpfp or the hpfp either, without seeing the logs when it goes iffy.
Like I said, another member had the same issues and it was down to the fuel filter.
I'm just trying to advise you from my mistakes.