In love with my fluence

<p>I m driving renault fluence expression 2012 model.since 2015 ive been taking it to renault Wonderboom in Pretoria. Complaining about anti pollution and spanner signs on dashboard that dies not disappear.They say they did repairs but after two or three days appears again and have to take back to them,its frustrating.last month I asked them to diagonise what might be the problem. They said is oxygen sensor which they say they installed new one, a week ago are received my car on a friday, on sunday the signs reappeared.pls help because im loosing trust of their technicians who I think put me on risk of damaging the car engine.</p> <p> </p> <p> </p>