DMF's fail on all vehciles that have them, Antaras included. They're needed to iron out the torque impulses the modern TDi produces but a lot depends on how the car has been driven and what kind of loads it's had. It can also be just your bad. At least in your case it's covered by warranty, you hear a lot about manufacturers denying warranty and just blaming the driver, which is a hard thing to disprove.What year and model do you have? Also what kind of mileage?
2015 Antara Exclusiv 2.2 163ps Manual 2WD