Don’t disassemble it, take it to another dealer, seat belt issues should be replaced free if defective, especially on a new car. Unless it’s debris or owner caused damage. Also the retractors have SRS components that should only be worked on by a technician, for safety sake.
on your iPhone, go to menu, CarPlay, and then you should see a list of vehicles pick the one you don’t want to connect on startup, and switch it on/off as you please.