problem with car rental company

i rented a jeep 2 weeks ago from a company in sousa to travel to bavaro , but when we got to santiago there was a problem in the engine it was smoking and needed much oil ...so we called the company for advice they said to get a macanic to fix the problem and they would pay the bill on return of the jeep , so thats what i did. we continued as far a santo domingo and the jeep needed more oil and not to mention the amount of gas we put in the jeep altoghether 10.000 pesos.the journey was a nightmare in the end we got to bavaro ...the next day day the driver and my freind was returning the jeep to sosua they got as far as sanpedro and the jeep had the same problem again , so the driver left to take the bus back to sosua and my freind stayed with the jeep , but the police came and put my freind in the jail in san pedro for 3 days , then the people from the car rental company came to bavaro to take me and my boyfreind to san pedro police station to identify my freind so they would release him ...but when we got there they changed there story was demanding 30.000 pesos the repair the jeep , so they then put my boyfreind in the jail because we dont have this kind of money , after many hours my freind who was realsed said i have my bike in sosua so they took the bike and released my boyfreind ..now they are saying they want my passport also , they still have my boyfreinds...and wont give it too him and they wont give my freind his bike so i dont know why exactly they want my passport , but they say if i give it too them they will give the bike back , but i do not trust this situation after they lied and did what they did at san pedro ...i have heard many other stories like this one from other people in sousa so it seems they just after money money money ...can anyone advise me on the best way to deal with this sisuation ...please

Daniel rent a car