vectra 1.9 cdti lost power?

I have problem with my 07 1.9 cdti sri vectra, it was ok but engine light came on and was running poor at idle. it was due a service and a new clutch at the time so had it all done at same time. I knew the egr valve was stuck open and got garage to clean it, this fixed the problem and car ran much smoother. however he was meant to do a filter change at the service with me supplying the oil. I would have done it myself before it went in but was given wrong filters so did not bother. anyway called the garage to check on progress and he said it was ok and could pick up in an hour i asked if he had done everything ie change the fillters and put the oil in,
this seemed to be news to him but then said yes its done. get car back and noticed that the oil had obviously went in the car but the wrong filters were missing from boot i had been wondering all week if he had changed the fuel filter as it was manky next thing car looses power on motorway as if no fuel nothing from throttle. 2 mins later ok again stuck the foot down to test and happened again.so let it idle looked at fuel filter housing fuel residue all over it. i conclude that he opened filter seen it was wrong and fired the old one back in along with all the s*"t not attached properly and if fuel can get out then air can get in.also filter out let? on side of housing that runs to the engine was slightly out pushed this in and got home with full power. but engine light is still on would the fuel starvation keep this light on? or is it linked to all the work he has done? or is egr still faulty but is idleing fine again and not shuddering. if you have made it this far any ideas. cheers