There seems to be an element missing here. Back in 2017 I had the engine go on my well cared for 2007 Impala with 184,000 Klms. I replaced it with a used 3.9 litre engine with about 70000 klms from a wreck. The engine had to be shipped in from 300 klms away to have it installed in my car. Paying GM dealer shop rates, they had partially disassembled my old engine to determine it was f**ked, shipped the engine, R&R the engine and "all in' (shipping, labour, miscellaneous, engine cost, sales tax,etc) it cost me 4500 bucks. And remember that's paying dealership labour rates. It ran like a charm, BTW. How did there get to be 5500 bucks over and above the cost of the 1500 engine? This guy sounds like a total crook and likely inflated the cost as he went along. I think you should take this guy to court.