One of the things that is often over looked when people consider quality of service is the impact of the consumer on that service. Sometimes, rarely, people consider the concept of "high value" customers and the idea that these should have some form of "fast track".
There is however another piece that impacts on both the cost and the quality of service, and that is the ability of the consumer to subvert the "standard process". Returning from our Christmas break we had one of those annoying "bugger its broken" moments on something we pay a monthly subscription for. Basically the hardware is shagged but because its five years old we now "own" it and the buggers are trying to charge us about 70 quid (500 dollars by the start of 2008) to "fix" something which probably doesn't even cost 30 quid. I'm on the phone for about 30 minutes pointing out how this isn't fair.
Then in steps the Mrs with a "oh god just give it to me", twenty minutes later we've got a contract upgrade, better equipment and its costing us 50 quid to get something we thought about spending 100 quid to get and to get everything else all sorted.
What my wife new was that playing poker with these folks involves the "bluff" of canceling the contract, this means that she gets a much better quality of service than I do as I tend to follow the rules of "what is said to be available".
The point here is that while a system might have a perceived process, indeed a process which the server side wishes to enforce and that a rigid enforcement of that process can lead to lower customer satisfaction and potentially reduced value being handled by the service.
What this means is that it is actually not up to the server to purely dictate a straight process and response to the consumer it is up to the consumer and producer to negotiate the right result for both parties a QoS policy that assumes that the producer is the final arbiter of quality is liable to produce a very unfriendly service and one which doesn't interact with people in the manner which they wish.
Its fine for the service to give you three options, but if my wife can't find the fourth then we'll be going somewhere else.