how to get abandoned car tittle transfered to car repair owner's name?

how to get abandoned car tittle transfered to car repair owner's name?
my auto repair shop has a few cars abandoned after they were repaired by customers whom either had no money to pay or for whatever the reason was for them to abandon their cars. we need to find a way to get the tittles in our names so we can sell the cars to make up for the repair fees. help!!!