Its not funny. There have been many such incidents of such rip off and if u resist they gang up and threaten u to the extent that u feel safer in giving away the money. This is open robbery and police knows it happens yet....
Very sorry to hear your loss bro, if indeed it is a must to visit then try not to take the car there or park it on the opposite side of road. Do not repair anything from there, just buy the stuff u need and have it installed by your trusted local mechanic.