SiriusXM is sweating right now
replies(2):
If you call and tell them to stop, they will only stop for 2 years then resume. Or resume when you take your vehicle to someplace that (re)sells your information to them.
You can get anything you want at Alice's Restaurant (excepting Alice)
The USPS has an FAQ about mailing bricks, but it won't load for me. I do know they are allowed to throw away trash, and they could interpret a brick as trash.