Ford Focus TDCI Cutting out problem?

Hi All, Am in some desperate need for help... have had my focus 1.8 TDCI Sport 53 plate for 2 weeks. And its cut out on me a few times, usually when on dual carriageways or whilst going up a hill. The Glow plug light will come on and i will lose all power.

Now ive read a few comments regarding this and someone suggested a cam shaft sensor. Have had this changed and the same thing has happened.
The diagnostic machine also shows up code 0251 Which apparently is Fuel Pump/ECU. Ive been told a fuel pump could cost me 4 figures to fix, but none of the garrages will take it on as they feel it could be a sensor also..... anyone got any ideas or previous experience? or where i could take it to get a more definate answer as to what is could be?
Many Thanks for your time