Rent to own (Car) Please advice!

Few years back i rented a car here in Doha but later converted to "rent to own" with a legal agreement from both parties, i finished the payment in year 2013 but the ownership has not been transfer to my name. Anytime i called the company they keep on telling me the company has problem with Traffic Department that is why they can not transfer to my name, recently the company refused to pick my phone call as the company has folded up, even the owner of the company that used to pick my phone call stopped picking my call. I have all my papers(copy of the agreement, complete receipts for the payment of the car). Please what do i do? I need your advice.