Engine Head Gasket Failure problems of the 2003 Dodge Intrepid

I never had a major problem, except cloudy smoke coming from the tailpipe and an oil. All of a sudden the oil light came on it began to over heat and stopped in the middle of the interstate. I had it towed to landmark Dodge, the mechanic said it was the timing chain (upon my arrival, I explained the mechanic, what happened to get to the point where the vehicle stalled, he immediately told me it was the timing chain and I needed and engine, without doing a diagnostic. I asked the mechanic to do a diagnostic to be exact and not guess what the problem might be. They responded by having a sales rep call to try and sale me a vehicle). I wanted a second opinion, therefore, I had it towed to steve rayman Dodge that's when the mechanic discovered I needed an engine for sure after a diagnostic was performed. The mechanic said it lost oil pressure, and had sludge build up. At first, the mechanic said he could replace the head gaskets for $3000. 00 but he could not guarantee the motor would last. Upon further investigation, that's when the mechanic discovered the sludge build-up, no oil pressure and I needed an engine. The mechanic at landmark recognized the nature of the problem without a diagnostic and tried keep my car for non payment of service that was never performed. Is this common for Dodge/Chrysler vehicles? as a consumer, I have the right to investigate, protect and pursue legal action.