I'm sorry to hear about your experience with Apple.
I am not an expert on Apple's policies but I've heard before that if you have an Apple device in for repair at an authorized place multiple times for the same issue, they'll replace it entirely.
I'm not sure if they provide a new or used machine as replacement.
Either way, I'd go to the store and politely show them the test (run it in front of them). If it shows the error, ask them (politely) to explain why the error shows if nothing is wrong.
Be calm, polite, but firm. If they want to run a test, have them do it in front of you and show you nothing is wrong.
Have them look closely at your repair history.