2004 Hyundai Terracan Diesel fuel filter

Hello, I live in Costa Rica and at the mercy of many bad mechanics. Last year I had to replace my injectors and now again my new mechanic said they are bad. He said I had a bad off market fuel filter installed and it dispersed eices of the filter thru out my fuel system and needed to replace everything. So now after 1 1/2 months I get the car back but he said I need a new thermostat and this is why I still have black smoke? Please help is this possible. The car is up for sale and I am buying a golf cart. Thanks Sue