Thanks for all you are doing Hoody007, much appreciated.
I have a few frustrations with engineering's response to you:
1) Irrespective of whether it is reproducible across your devices, it is reproducible on other models of cars across the world as evidenced in this forum. So that should should raise a concern on their part.
2)Others in this forum (for example DaveOJr) have clearly stated they have reproducible problems on multiple devices beyond cars, so that is contrary to what they are telling you in (1). Perhaps engineering should contact some of the others on this forum.
3) The iPhone 15 Pro and iPhone 15 Pro Max are sold as having Bluetooth 5.3 functionality. In principle, Bluetooth is backwards compatible where to my understanding, 5.3 is compatible with devices back to 2.1, circa 2007.
4) Reflecting on Point (3), at no point during the sales process was I advised that if I was driving a 2013 Audi A4 that I should consider buying a new car in order to get access to the full functionality of the pro models as backwards compatibility of bluetooth was not guaranteed (or is it even tested?).
5) Why does an iPhone 6, XR, 14, 14 Pro and 15 all work in my car, but my 15 Pro doesn't. What's the difference between the 15 Pro and the other devices?