And this latest missive from MS Surface Support:
"Thank you for your reply.
*We sincerely apologize that that option we provided to you is not the option you preferred.**Please know that it will never be our intention to cause you any kinds of trouble with your device.****We would like to suggest as well a purchase towards a brand new device.****Having a brand new device is an advantage because aside from the 1 year warranty provided you can also get a Microsoft Complete Plan which provides an additional warranty extension up to 3 years depending on the coverage that covers any physical damage like crack screens or even liquid damage caused by accidental spills.*Meanwhile, If you were to decide, we would like to know what would be your preferred solution for this case for us to check if there is anything we can do about it."
So, they have thrown in the towel and suggested to me that I buy a new computer. I could spend $599 and replace this computer but I do not trust the Marvell adapter. They did not directly answer my question regarding whether or not the replacement computer has the Marvell BT adapter - but I can connect the dots. They said it was like-for-like.
To the thousands of you worldwide who have this Marvell AVASTAR Bluetooth radio adapter problem - it's not fixable. I'm sorry this happened. I love my Surface Book 2 but its functionality is severely diminished w/o BT capability.
Maybe you will be luckier than me by owning a device that is still within warranty.