carplay audio doesn't work

My carplay audio doesn't work. Siri is fine, maps are fine- but music, pandora, audible, anything "audio" fails continuously

I've tried every troubleshooting step on the apple site and on every tech site I can find.- Nothing works.

I've asked apple support for help (2 days in a row they can't get an lvl2 person to call, or answer anything- I keep getting the same lvl1 helpdesk with the same book, then they escalate, then they do not call - today after repeated chats, they called the wrong number apparently (I only gave them the right number 4 times in the past 2 days)

Does anyone know how to get carplay audio to work? I'm not using carplay at all now; I just hook the iphone in via bluetooth and everything works fine- as long as carplay isn't on.

in short, it's not the car or the phone, everything works great on a bluetooth only (think android type) connection- but carplay has never worked since I bought the car last month. so can anyone tell me how to get this apple "product" to work?