A few decades ago a chap would have taken dodgy wipers, lights, shattered toughened windscreens and other minor maladies in his stride without sounding a bit, well, hysterical. Anyway, the usual fault is either the bonnet switch, seized drivers side spindle or failed motor. If the bonnet switch was at fault the dashboard would say it was open and they still work at speed and if it was a seized spindle you would not be easily able to move them so it sounds like a failed motor. A new motor from Audi is around £235 and takes about an hour to install but the Audi system says just over half an hour which is a little optimistic! The motor is not available aftermarket as far as I can see. If it is the spindle that is seized, the you have to buy a complete new frame assembly that comes complete with the new style more reliable motor for.....errr.....the same price as the old style motor WITHOUT the frame, well that's just daft! The complete system is Audi part number 8P2 955 023 N.