If you go on TDIclub, there's a VAG-COM list.
The VAG-COM is the tool that is used to check the ECU's parameter (the timing also).
If you could get someone to plug it in your car and see what the timing is like, you'd know where you stand.
As long as it's in specs (you see it on a graph, from 25 to 75 is the range, 50 is about in the center. It's better if the timing is advanced.), no mechanic will change it.