Antipollution fault?

I'm South African and I have a Peugeot 1.6 HDi, bought new in 2008. My car started jerking, clicking and blowing white smoke while driving on the high way this winter (June 2010). I checked with the service manager at the Peugeot garage who advised me that the reason for this was because it was winter and therefore water may have been trapped in the diesel. He said I should just run the car this should clear.
The problem reoccurred two months later where the car just lost power and I had to have the car towed to the Peugeot garage. They conducted a diagnosis where they indicated that the injector pump, injector 3, injector rail and return pipe would need replacing. This was difficult to understand considering the car has 49k on the clock.
I took the car for a second opinion and the mechanic indicated that the diesel injector needed replacement as well as the EGR valve that would help with the engine sluggishness. Least to say, after the replacements, the anti pollution light just came back on, and the car still had this clicking noise immediately thereafter a plume of white smoke follows and the car slows down close to a 20km crawl. It helped to stop the car for few seconds and thereafter it would go like a bomb.
Please help before all the mechanics leave me out of pocket!!!