Think you have put this on your own head....
You talk about the problems while driving the car, so you probably went to the dealer to talk to them about it. And you also mentioned the overfilling problem and now they have something to blame on you, even if the problem is there because of you or not ( go for that expert opninion???, if he can prove the problem is not oil related then maybe...)
But as angie has said (with fire
) there is not much left you can do, and by saying its a new car, i presume you have done quite some miles already...
I hope the engine damage is not to severe and the cost will be as low as possible.
grtz and best of luck