I had my Mk3 16v serviced at VW a few months back, it had an 80k mile service i.e the biggest one. I was quite pleased. They did all this
Oil + Filter
Air Filter
Pollen Filter
Spark Plugs
Pas Fluid
Washer fluid
All Wiper Blades
Checked gear box oil
Checked Brake fluid
Replaced brake vacuum hose
Topped up anti freeze
Full inspection of brakes, exhaust, suspension, etc, etc (got a big list of checked items)
Full and very good Valet inside and out
Report on all faults - not many found but they were thorough enough to mention a cracked front reflector.
They even got me a Golf courtesy car because they said i might find a polo uncomfortable (i'm quite tall).
Total cost was ?220. A bit pricey but worth it in my opinion.
So i guess it's down to luck wether you find a good or bad dealer.
VW service history is sought after by buyers, so if you don't intend keeping the car long then i say pay a bit extra and get the vw stamp.
If not just use a trusted garage and save the money.