mokka 1.4 automatic

I bought a 2015 Mokka took it for the first drive home and after 3 miles of 30 MPH road it seemed OK then I put my put down in the 60 MPH and large amounts of Smoke and loss of Power so car would not go over 45 MPH - The garage say it is Oil in Pipes that it needs Flushing & I saw a Webpage...