The problem here is simply a bad service experience! These are pretty simple machines in many respects, so simple trouble shooting following conventional logic!If you Google around you'll find that an Onan 2800 goes for about $2,300. But it doesn't seem to make any sense that an almost new unit would be uneconomical to repair for anything short of a major and destructive internal failure. It may well be that they don't really know what's wrong and would rather replace it (at your expense) than continue to troubleshoot. If that is the case then it's time to take it to a more competent repair station.