A6 C6 esp fault and handbrake malfunction

[Quavers]

My 2004 A6 2.4 is throwing up the above. Took it to auto electrician who re calibrated the steering angle sensor but told me my rear calipers were getting tired. Was ok for a while now lights come - they go off and come on again. Battery is in rude health (checked 11.9v when cranking). Car has 59k on the clock and is mint condition but I am mindful it is pretty worthless so I am not prepared to chuck £££ at it.

Anybody hadanything similar?