Air leaking into fuel line, suspect fuel filter housing.

I have done a "rountine" maintenance of changing the fuel filter on a peug 206 1.9d 2001 (y76enp). A ten min job turned into a nightmare 6hrs. The engine will not run properly.A new filter and seals were put in, fuel lines reconnceted and system primed, but because of the air in the line, car doesnt start unless assisted.
I have AA out and they could not fix problem. We primed the pump, tried the old filter, tried puttting gloves over pipe work joints. Engine would run but then stall if left alone.I am trying to eliminate step by step where leak is coming from, but to no avail so far.
I suspect the seal on the underneath of the fuel filter housing, accessible by undoing bolt and removing. Or there is a leak in a fuel pipe conector, probably the fuel primer plunger.
Have you ever come across this problem, after changing a fuel filter?Any help greatly appreciated!