Diesel focus wont start

Today I was climbing a hill and my 1.7tddi focus gradually came to a halt as if fuel was starved or indeed the cam belt had gone (this I checked). There where no strange noises and it was as if there was an electrical fault/fuel fault on a petrol engine. Once I checked the engine it did appear that the diesel filter was loose consequently I presumed air had got into the system. Anyhow a recovery vehicle towed me to the nearest garage after many attempts at bleading it (oh the car did fire up using a little sniff of Spray start but then stopped) At the garage there was the usual tut tut and a suggestion that the timing belt may have moved a few notches, thus bending the valves hence the pump timing out of sink (is this realistic). He stated that it would be a major inernal time consuming job. I have checked the belt and cannot imagine how it would leap over approximatly 23 teeth, although it could be tighter. I just wondered if anyone has any ideas as I would rather not have the inconvienience and cost of taking it for a diagnostics if it simply needs bleeding further?. Oh I know that when air does get into the system they are a dog to get going again, previously I towed it some distance, however I have been advised against this. Does anyonr have any ideas!

I cant speak for the diesel focus, but i can remember when we used to work on diesel vw golfs and jettas, sometimes we had to remove the fuel filter and actually fill it with diesel fuel and re-install it to get it to suck fuel on its own