Can they garnish my wages for non payment of vehicle if I'm willing to give the vehicle back?

They are not required to take the vehicle back. Rather, you should sell it and apply the money to the balance owed if you do not want it. In Louisiana, a sale occurs upon agreement of the price and the thing. The vehicle is yours, and you owe them a debt for whatever you borrowed. As you are under garnishment, they likely have judgment adding attorney fees, court costs, judicial interest and a sheriff's commission. By not addressing this sooner, you end up owing up much more than you borrowed.