I have a 2002 that is dropping in the front if you leave it for two days. I had a good chat with a senior guy from audi and he said it will be a leaking joint. To find it you simply squirt on some detergent and water and see where the leak is. Apparantly they use standard air parts that you can get from any compressor type company. Once fixed you should be fine.
Easy enough to fix yourself he said.
