I had a similar issue with my 2003 A6 2.7T. Dealer wanted $6700 for a new trans and three weeks to get it in (I guess they don't rebuild transmissions). I ended up taking it to a local trans shop and got it fixed for $1800. The guy told me the drum in the trans was all beat up. $1800 is better than 7grand. However I am having some major issues with my car now and I think the trans might be having problems again (different problems now).