Make a distinction between the car manufacturers recommendations and the dealers. Many dealers, not just VW, come up with recommendations in addition to manufacturers.
That said,
This is what VW says to do @ 20k miles for your car: Items to be serviced: Engine Oil - change Engine Filter - change Timing Belt - check Water Separator - drain Fuel Filter - replace Windshield Washer Fluid - check level Automatic Shift Lock - check operation Brake System - check damage/leaks, pad thickness, fluid level Wheels - rotate from front to rear Air Bag System - check function/damage Battery - check electrolyte level Engine - check for leaks Pollen Filter - replace Cooling System - check level Transmission - check for leaks Tires/Spare - check condition Driveshaft - check boots On Board Diagnostics - check Diagnostic Trouble Code memory Door Hinge - lube Headlights - check and adjust if necessary Exhaust System - check for damage and leaks Sunroof Frame - clean and lubricate Road Test - check system functions during and after
$400 is not out of line since most diag cost about $90. and if the dealer does a good job, it's fair and equitable.
BUT . . some dealers don't and many of the checks can be done by you.
If you're not mechanically minded and somewhat nervous, this is honestly fair and okay.
Good luck.