I've had the 3G SatNav in my B8 A4 for nearly two years. It's had various updates etc and I still get incorrect instructions at roundabouts. e.g. "take the second exit" comes too late so it's actually the next exit that's needed.
I've got the latest dealer installable updates and also the 2011 maps.
Audi Customer services have told me they believed this issue was resolved by a previous update so were not aware there's still an issue. My dealer thought the same.
Audi need feedback on this from owners with the problem or it won't get resolved.
Please ask your dealer to raise a DIS Report with Audi UK so that they can pass it on to Germany for resolution. I thought dealers would do this automatically should an issue not resolve a customers problem but it seems it doesn't always happen so please request it.
Fingers crossed we may get somewhere.