Budget, Avis, Tilden
Stick with the big boys......Stay away from the Mom & PoP Rent a Cars!
There are many horror stories in the DR1 archives regarding this. ( Do a search )
Inspect the car very well before taking it away, They do and will put a US $1500.00 block on your Credit Card , in the event you bring it back damaged your card will be zapped and the bill will be waiting for you when you get home on your Visa/Mastercard.
The Big three Rental companies are less likely to get as greedy as the small indepdepents...
Good Luck
Gringo