Peugot 307SW1-Depollution?

Reading this Forum it appears that this problem is very common with Peugot-pity i did not know this before i bought it.Have Peugot 307SW1-Diesel and 2 year Warranty expired in June.What should i do as i have this problem now and know for a fact that local dealer will not have a clue what to do and wil want to charge me an arm and leg.I need the car for work.Help!Laura-cannot access your e mail as you seem to be dealing with Peugot but have also had this tapping noise-right from delivery but never resolved.Should i contact Peugot or Watchdog-but i need my car!!!