On Star module broken

I’ve been having trouble with losing audio in my 2023 Silverado from the first month of purchase. I took it to the dealer mechanic, but couldn’t replicate the problem. I told him that people were all over the internet complaining about it. He said he didn’t follow message boards. Maybe he should. He said there were no records with GM discussing such issues. He acted like he didn’t believe anything was wrong with the infotainment system. They looked it over and found nothing. So, okay… I drove it another week or so the  audio failed again. So I took it to the dealer mechanic again, did not turn off the vehicle, and went inside and brought the guy out to the truck. “Yep! That’s a problem. It’s common on these models. It’s nothing we can do about it.” So we both shrugged our shoulders and went about our business. NOW OnStar has failed. Today’s dealer mechanic says it’ll need a 48 hour diagnostic test to figure out what the problem is. I’ll need to schedule one. But y’all are telling me what I believe to be true - without a diagnostic test - that I’m looking at getting charged $850+ to replace a module that was most likely defective the day it went on the vehicle.