Alternator/generator/regulator problems of the 1999 Saturn SL2

I called mr. Akinbusola desola akintola harrison on 08/03/06 for 99 Saturn Sl2 for sale over craigs list web-site date 08/02/06ad#189307708@craigslist. Org. When meeting him in person I asked him if the car had any damages, accidents or perhaps to disclose any information about the car. He said that the car is in perfect conditions its a clean car, no accidents, no dents the car was in good condition. When I asked him to bring the dmv paperwork along with registration and pink slip he only brought the dmv forms to fill out. The seller lost the pink slip, but with dmv form reg 227 you should receive a copy. Once we finished with the forms he asked for the payment to be in cash $2,500. After the transaction I drove him back to his home. He advised me to change the cars battery because he got the wrong one (a difference of $30. 00 already!) I headed back to work & this car stopped running while still driving I parked it over my job's parking lot. I checked the registration: which was issued on 7/11/2006 pr/hist: salvage!!! he managed to fool me & mr. Khan as well! he brought a printed out sales contract along with the dmv forms which seemed fair. Mr. Akintola harrison kept the vehicle's registration with him at all times until he got the papers filled out, and signed and the $2,500. 00 in cash. He released the car's registration placing it in between of all the dvm documents. I called him on Monday 08/07/2006 until now asking him in good faith to do a fair exchange (this vehicle has been parked over where I work since I bought it) in a friendly manner I asked him to get my money back with no hard feelings & when can we resolve this issue? I did changed the battery as requested (a $30. 00 loss on me)mr. Harrison called my work number and told me that he has spent the $2,500 already; instead I should buy a new alternator! please help me with advice in how to approach this event!.