Dave's Auto & Pro-formance LLC Dave's Auto Dave blew up engine of my vehicle and refused to pay Overland, Missouri

I bought my vehicle to Dave's Auto because the temp light was flashing and the needle was over 50%.  Dave inspected the vehicle and did some research online and determined that the problem was air in the coolant.  To fix it, he said I should take the car home, allow it to cool overnight, and fill the coolant to the very top.  I asked, the very top?  Past the fill line?  He said yes, the excess coolant would simply boil out, that the coolant cap was designed to release the excess coolant.  I did as instructed, allowing to cool overnight and filling the coolant to the very top the following morning.  I did not notice a change during my drive to work, temp light still flashed and temp needle reported the same temperature as before.  That evening after work the needle passed 75% and the temp light changed from flashing to staying on continuously.  I took a photo of the gauge and text it to dave and called him.  He asked if coolant was boiling over.  I checked, no.  He said it's ok then, that this was normal.  The next morning as I drove to work the needle passed 75%.  I pulled off the highway and called Dave and the needle reached 100%.  He again asked if the boiling over.  I checked, didn't see any liquid under the car or around the coolant reservoir.  He said it was fine then, he had just seen the car 2 days ago, less than 50 miles ago, and it was suppose to be doing this, but I could bring it in after work if I was worried.  I continued to drive to work and the car died.  I pulled over and just as I pulled over Dave text me to say maybe I should stop driving.  I called him and said it was too late, car already died.  He offered to have it towed to his shop.  He checked the car and said the engine was blown and would cost $12,000 to repair.  I told him I wanted a second opinion (how could I trust him after misdiagnosing the problem before?) and a engine specialty shop said they could repair the car for $7,000.  I asked him to pay half of the repair and he refuses, claims he never saw the car, that I'm stupid for bringing it to him and I should have taken it to the dealer to begin with.  That's great advice, don't take your car to Dave, take it to a dealer or someone that knows how to repair cars.