What does the new oil leak have to do with redoing the turbos again. Two different problems. Oil could be leaking from any number of places and the turbos would be fine. Even if an oil line to the turbo, left or right, was leaking the most you could be in for would be a new oil line and copper crush washers and if they installed the motor and did the work on the turbos they should stand behind a minor problem that they may have induced.