2007 Vauxhall Zafira white smoke from exhaust

my car went into limp mode so took it to my local garage and managed to get it going agian but advice me to take it to main dealer as white smoke came out of the exhoust after 5 mins of drivingbut if i switch the engine off and then restart straight awy drive with no white smoke. Walker in Worksop diagnosed as egr and inlet manifold wanting replacing at a cost of £1200 as was out of work i purchased the egr and fitted it my self no effect so i took it Pentegan at Mansfield they diagnosed pipe connecting egr and particular filter was leacking as it was pached up with garden hose (even though Walkers did not mention this 3 weeks previous) they quoted £250 for repair which i agreed to when i picked the car up the price shot upto £480 when i asked why they said it was cos i put the egr valve on and not put the gasket on even though the gasket was the one from the egr to the pipe they replaced This lasted 2 days before white smoke pumping out again replaced inlet manifold had all head reconditioned and new injectors fitted and after spending £2500 still the same problem had it diagnosed again by main dealer they stated no fault with car but recomended a new paticulate filter ran out of money and patiences any one had similar problems