Finally, this issue has been solved and my car is back in full working order…
After being messed about by my local Audi dealer who couldn’t diagnose the issue after a whole day but wanted it back at further cost to carry on trying, I sacked them off. Absolutely useless. I also approached a handful of local so called Audi specialists, none of which wanted to know. In the end, I contacted a company down in St Albans called Hazzydayz who specialise in retrofits and MMI repair.
My issues were being caused by the central convenience module which had sadly died. They also diagnosed an issue with the internal battery on the CANbus gateway module. I had them both replaced and at a very reasonable cost.
In short, if you have MMI issues and you are out of warranty, take the car to these guys! Extremely helpful and knowledgeable and I wouldn’t hesitate to use again.