air in peu 206 HDI fuel system?

Hi, i have an 06 plate peugeot 206 HDI that wouldnt start. The RAC came out and said there was air in the fuel pipes and manually pumped air through...car started. Next morning same problem. RAC sealed all possible locations where he thought the air might be entering on the plastic fuel pipe system. car driven 120 miles back home. Same thing next day engine would not start. Car taken to a local garage who said the problem was with the fuel pump in the tank and replaced it, however the car still not starting! Feeling very worried the mechanics seem baffled...