Boat Repairer Problems

I'M A NEW BOAT OWNER AND I TOOK MY 24' BAYLINER IN TO GET THE WIRING REPAIRED AND THE TOYS PUT ON IT (STEREO,GPS AND VHF RADIO)I GOT THE TOYS PUT ON AND THE WIRING DONE, BUT HE DIDN'T REPLACE MY PROP OR FIX THE GAUGES BUT HE DID REDO THE UPHOLSTREY WHICH I NEVER ASKED HE TO DO, I ASKED TO GET A PRICE FOR ME ON REDOING IT A CERTAIN WAY IN LEATHERETTE. HE NEVER GAVE ME A PRICE AND WENT AHEAD AND DID IT IN A DARK BLUE MATERIAL. I GAVE HIM $1000.00 TO START AND $3000.00 AS HE ASKED WHEN I GOT THE BOAT PICKED UP AND A WEEK LATER HE FAXED ME A BILL FOR ANOTHER $12000.00, I'VE TOLD HIM HE WAS OUT OF HIS MIND THAT I WASN'T AND COULDN'T AFFORD SUCH A BILL AND I DIDN'T AUTHORIZE HIM TO DO ANY OF THE WORK HE SO CALLED DID. WHAT ROUTE DO YOU THINK I SHOULD TAKE WITH THIS GUY? I CAN'T BELIEVE IT WOULD TAKE 8 HOURS TO INSTALL A GPS AND ANOTHER 15 HOURS TO INSTALL RADIO AND VHF RADIO, PLUS 25 HOUR TO REPAIR WIRING