Was laying in bed this morning and was actually starting to wonder the same
Lets say it does, do you know the values?
I'll see if I can reach my PC at work at have a look at the documentation about their network we use (epacity ip vpn)
Edit: Just checked and yep they do support QoS although they call it CoS
You have to mark your traffic as being CoS (you have to set the so called "CoS bits/Priority Code Point" value). Your ISP needs to honour these bits and carry out the same configuration throughout their network in order to make it work (and mind you, it only works until their own boarder).
Check with KPN if they honour your CoS marking, or if they "re-colour" it themselves (in that case you need to tell them what traffic to mark).