Car surrender now I'm listed

I surrenderd my car due to the car being faulty and no one could assist Renault said that it's out of warranty as service was skipped and the dealership said they gave me the car fine I have paper trail of all that me returning the car in Jan I was quoted an amount and advised that they will call and inform me once the car is sold when I check my score account is out for collections and I'm not even advise if it sold or not it's handed over and no company called me every month it's gaining interest while I sold it back to them I owe now 35k in overdue monies cause it was not updated the car is not in my possession I need answers as to what is happening with the. Are