Hi SFIRTH.
I did in the end! As I mentioned in my previous post I was working with a private ex-Audi master tech / mobile mechanic, and he managed to find a company to take a look at it who ultimately fixed it.
I believe it was Hazzy Days, would suggest giving them a try directly.
https://www.hazzydayz.com/
Essentially, mine went back and forth a few times to repair blown amp chips two-three times, but the same reoccurring issue kept blowing them, hence concluded it wasn’t just the chips.
Eventually it went back again and they had a senior engineer look at it, and while I can’t remember the exact reason, it sounded like that there was some unwanted contact with the top of the MMI metal case and the PCB which was causing the issue?
Not sure exactly what they did, but my understanding was it wasn’t something they’d ever come across before, hence they took a note for future repairs.
I am making an assumption that you have the exact same MMI unit as me, but even if not I’d recommend trying them anyway.