Car Repair Shop Dispute (continued)

Location: Colorado

My previous post

I’m continuing to have problems with my auto repair shop, with some new details, and am unsure of my next steps.

To recap the previous post, I took my car into a shop for P0011 and P0017 codes. They replaced both camshaft timing sensors, and sent me home with the car at closing (5pm), not mentioning an oil leak their oil change service saw, no recommendation of further service or warnings. Codes were cleared by the shop before handing the vehicle back, this I have confirmed with them in person. I then, after checking oil levels, hit the interstate and drove 50 miles out of town, where my car showed a blinking red oil light, grinding noises, sludge coming from gaskets, black smoke, and codes for the original issues, and several more relating to engine knocks. I had the vehicle towed back to them, and told them to inspect their work only, do not perform additional repairs. I sent this to them in writing as well, and had it confirmed received verbally afterwards.

The update is now is that the issue by their admission was the O-ring on one of the sensors they replaced. Without my authorization they drained all fluids from the car, and redid the sensors, and told me they’d done extensive test driving of the vehicle. They then told me to pick the car up again at closing, I refused and came in the next day. When I came back in the morning, they said that the p0017 code had returned and that there was likely an underlying issue, that they’re avoiding admitting any liability for. The engine knock codes have been cleared off and only p0017 shows now. They’re trying to tell me that the engine is in the exact condition it came in originally, but avoiding wording anything like the car works, or can be relied on for a long distance.

At this point I am worried my engine is permanently damaged, as it cannot be good to drive a car at 80mph with no oil in it. There are also sludge marks from the gaskets surrounding the engine that were not present when I brought the car in. I do not know what happened to the engine knock codes, if those were sufficiently cleared just from getting oil back in the car or what. The shop refused to provide me any technician notes, pictures, video, the original replaced parts, the original fluids, or any freeze frame data from their scanners. They did verbally confirm their techs were clearing codes to me however.

I have a larger dealership service center now doing an independent inspection. My legal question is this, is what they did a violation of the Colorado motor vehicle repair act, in doing work without my authorization, that I in writing told them not to do? I brought this up to the service manager who said this only applies to work they’re charging me for and they did nothing wrong, even after acknowledging that he received my written demand not to do further repairs.

Beyond this, if my engine is ruined or damaged per the latest inspection, how can I pursue this if they seem to be actively destroying all evidence of their work, old parts, oil, picture, notes, etc?