... the secret handshake for replacing the control arms is "noise like squeaking or groaning" coming from the front suspension.

With a 100k on the clock, you are almost certainly due to replace some of them. I strongly recommend replacing ALL of them if you do any. Maybe you get Audi to replace the lowers and you pay for the uppers, or some variation on that theme.

Good luck

Just don't let them charge you $700 for floor mats. ;^)