Sorry, I was referring to the range estimate being based on your driving style. That part is untrue. Tesla employees, unfortunately, often say things that aren't technically true. The rated and ideal ranges are each determined by a fixed equation. The Energy App projected range is based on driving style, that's the only one, but it doesn't show on your instrument cluster. I believe Tesla employees are confusing the projected range in the energy app with the EPA range that gets displayed.
Tesla's resistance doesn't make much sense to me. Others have been given the same response initially, but upon escalation Tesla has always done further investigation on the battery and caught issues that were there. Perhaps their policy is different with CPOs, I don't know, but it shouldn't be. The warranty is the same.
Don't talk about "actual mileage" in your car. That confuses the issue and opens the door for Tesla to claim your higher Wh/mi usage. If this ever ends up in front of a judge and jury, they might think that's significant to your case even though it isn't. What matters is that your displayed range is at least 20% below what was advertised at the time you purchased your vehicle, and that difference was not disclosed to you.
A simple analogy would be buying a used gasoline car where the vehicle had a 20% smaller gas tank. The dealer advertised the manufacturer's specified range, but did not disclose to you that the particular vehicle you were buying had a 20% smaller gas tank. I'd be miffed.