anti pollution /braking & immobilizer fault

I have had an 807 (04) for 3 yrs and it has always came up with anti pollutiion fault, last year it started coming up with braking fault and just recently it broke down in france when immobilizer fault appeared. as each fault appeared they have all been checked by peugeot diagnostics and no fault has been registered on engine management system? it is now on its way back from france and i fear a huge bill!! any suggestions?