The incident I was thinking of happened way before that one. The group of Canadian lads who met a Haitian and a Dominican and someone knew someone who could get a good deal on a private rental in Sosua. So they went ahead & rented; unbeknownst to them the vehicle had been the scene of crime in the murder/attempted murder of a prominent Dominican businessman. Of course the guys renting the car knew nothing about this, but they got stopped by the police, the vehicle impounded & the driver & passengers thrown in jail. One of the young men was terrified of what was going on inside the jail & got a message to his sister in Canada. She & her husband came down to help him; BushBaby picked them up from the airport so they were met by someone who spoke English & took them to their Consular rep. at Cafecito where they were also met by Gringo (Larry C.) who very kindly accommodated the couple free of charge.
For the Canadian young man, despite having his sister & brother-in-law's help, the support of an experienced Hon Consul who knows his stuff, plus a couple of long term expats helping the sister, this was still a nightmare experience. And all because the car rental was done 'by someone who knew someone'. The amount of money 'saved' in the cheap rental was paid out at least 10 times over in lawyer's fees, airline tickets for sister etc etc.
Don't risk it. Go with the reputable agencies.