One chap on A5OC has just rejected a brand new RS5 from Vindi's (albeit it Northampton) as they damaged his car whist in for warranty work and then tried to patch it up (badly) without telling him! It's not been pretty; a sign that when a family business stretches it's legs and grows it can lose that sense of control that it had when it was locally based. Shame as obviously you'd found them to be good.
Funnily enough, on the wrong demonstrator point you raise, I've been struggling to find an 'appropriate' demonstrator for my change from S3 to S5. I could get a car, but then you look down the barrel of £7k of options to spec it up and you can't try any of them before you buy as most dealer cars are poverty spec! Leaps of faith required, but thankfully I found a very kind forum member on A5OC who was prepared to let me fiddle with his loaded S5 for a morning to determine what options I actually liked / wanted from the big list.
I'm always really pleased if anyone gets good service from any dealership to be honest, it's quite a rare treat these days and I guess my aspiration would be to ultimately look to get objective data into a centrally managed database (in the long term) that charted UK Audi dealers performance based on a number of key performance indicators so that the community could access this and vote with their feet. People's experiences seem to vary wildly from person to person so it would be critical to get the questions 100% right, but given the forum readership it could prove quite useful information for Audi UK if we could ensure the data was robust.