I found this forum useful when I was investigating the problem so I'm posting my experience just in case it's useful to others.

I have just had a £3500 Goodwill repair done on my A4 B8 on a 60 plate with 75000 miles on the clock at Cheltenham Audi.
Audi UK paid 70% of the bill and Cheltenham Audi covered the rest.
I bought the car from Audi when it was 8 months old and have kept up a full Audi service history. Initially I did this during the warranty period but then carried on because it wasn't much more expensive than going independent and I had read about the oil consumption problems on the 1.8TFSI and the potential of a goodwill repair.

The car has always consumed oil, about 1l every 4000 miles but over the last couple of years that became 1l every 2000 miles and eventually 1l every 800 miles. I mentioned the oil consumption to the garage about a year ago when it was serviced and they said it should be covered by goodwill, but at the time the consumption was not below the service limit. I waited until the consumption figures dropped below the service limit and then booked the car in for the oil consumption test (£60 standard diagnostic charge). It took me a week to drive the 600 miles, then the oil was topped up and we confirmed it had failed the oil consumption test.
Cheltenham Audi then negotiated with Audi UK on the goodwill costs, it took a couple of weeks which seemed fine to me as these things do take time, then it was a couple of days to fix the engine. While the engine was apart they found a small leak on the coolant pump. They asked me to pay for the part which in my opinion was fair.

The repair has involved replacing the pistons and piston rings and the PCV is also brand new.

I had read about the potential of a goodwill repair on this engine, because it has a known problem, but until it all went through I didn't quite believe it was "a thing". Well it is, and I can only say thank you to Audi for resolving the issue. It shouldn't have happened on an engine of this age that has been service properly, but it did, and they have resolved it. Fair play.