The dealer told me that it really should have been chaged at 40k but they did not know that it was supposed to be changed.
Well lets see, seing as how the graphs below are what determine the service intervals for your car at the dealership...
First off GET OUT OF THERE!
Secondly YES your car MUST and is required to have the fluid replaced every 40,000 miles! Did you NOT read your owners manual that came with your $25,000 car? If not PLEASE take the time and read it!
Damaging that transmission can result in repairs in excess of $4,000 simply by not replacing the fluid every 40,000 miles. This is NO joking matter and is a very serious requirement for these transmissions!
I have a hunch you also do not use the required VW505.01 oil or VW507.00 engine oil either given your disregard for the other drivetrains MANDATORY servicing requirements...In which case if you have ignored this aspect (engine oil specifications on a PD engine) of maintaining your car you have an additional $3,000 of engine damage do the cam and injection system components!
Reference:
http://pics.tdiclub.com/data/500/TSB_17-07-06_Engine_Oil_Volkswagen_Oil_Quality_requirements.pdf
Old cam (40,000 miles of non 505.01 oil used) vs brand new cam side by side...
Ignorance is VERY expensive, disregard for not being familar with maintaining your car is inexcusible.
Before you throw a fit, even Honda, Chevy and EVERY other car maker has transmisison fluid change intervals ranging from 15,000 -30,000 miles, so this is not only common practice but common sense.
Onto the price, $900 is out right robbery! Cost of a fluid and filter are around $160.00
Labor and time $100-$125 and about 1-1.5 hours Maximum.
That being said given the fact you have severly exceeded the fluid change intervals, your transmission will require several short fluid change intervals in order to flush out the wear metals and clutch material. My experience is that it will take two fluid changes at 5,000 mile intervals to get the fluids wear metals back down to where you can resume 40K service intervals. This will/may be your only way to extend the life of the transmission at this point.
It's sad to see cars maintained so poorly due to owner neglect and ignorance...
DB