personally, i would do as suggested above in regards to trying to negotiate the bill down to a more realistic price. this happens often to stranded travelers. my mom's friend got shafted in a similar fashion when her car broke down on the way to vegas.
as mentioned, you never authorized additional repairs, regardless.
iirc, there are strict rules (regulations?) for mechanics in how much they can charge for specific work. if the guy is a tard and takes four days to fix a two hour job, he cant just go and charge you $4000! as mentioned above, there are given times for doing the labor (body shops as well). I believe they can be fined by the BBB or whoever oversees mechanics for doing this.
unfortunately, if he doesnt budge on the bill, then youre stuck, for now. the police wont do a damn thing and no one else will either (on the spot). if he plain refuses to budge, then pay the bill and plan to take recourse later (in small claims court).
here's where it gets sticky....
if you argue with him or seem pissed, then he wont accept a check (his legal right). he may demand a cash payment from you. this is fine, just make sure you get a receipt that states paid in full, in cash.
ALSO, take a
disinterested witness with you. like a co-worker, neighbor or similar. someone who wont "lie" for you (ie relative, buddy, girlfriend). you can take them too, but you need at least one un-biased witness to have rock-solid evidence of what happens when you go in there.
just because you agreed to four hours labor and whatever else, does NOT mean its in stone!! you are not a mechanic! you have no idea what it takes to fix cars. He is a licensed professional (assuming), he knows. you broke down far from home and took the recommendation of the tow truck driver (who is probably counting his $100 commission right now). pretty sure, this sounds like "undue influence" to me. someone in a "trusted" position (mechanic, doctor, caretaker, stockbroker, etc...) taking advantage of an unwary party.
my books are all packed away for moving but i did find this little snippet online.
"D. Undue influence
Short of duress, one party (the victim) may complain that his or her manifestation of assent to a contract was induced through the improper persuasion of another in whom the victim placed special trust and confidence. See R.2d Contracts 177. Improper persuasion may result from one or more of several factors such as constant pressure on the victim, an apparent need for the victim to decide quickly, unavailability to the victim of independent advice, and weakness or infirmity of the victim. Relationships creating special trust and confidence (often referred to as creating a fiduciary duty) include husband and wife, attorney and client, doctor or mental health counselor and patient"
now you dont go in to the shop, or court, claiming undue influence, im just showing you some principle to show you have a case.
dont even think about calling a lawyer, it wont be worth your $ and if you
do have a chance of winning, you should be able to pull it off by yourself (in SC).
when you go in there, take cash or a money order, and your witnesses. explain to him what others above said (how much it should cost/how many hours). be cool, and if he wont budge simply tell him that you will pay him what he is charging you but you will be seeing him in SC to dispute the bill. (and contacting BBB)
hopefully, he'll be smart and see that youre not some pushover that is just going to pay out whatever he charges.
if you do have to go to court, then you take estimates from every mechanic in town, including the dealership (which should be more expensive than anyone!)