Stop messing with the service advisors - if you feel you are getting the runaround ... call/see the service manager!! I have no idea if your parts/diagnositics should be covered under your policy. However, the extended warranty you have purchased should cause no additonal work for the dealership. Consider:

You take the X5 in and say - there is a "rattle" in the sunroof.
They call you back later in the day and say ... we can fix it, but is going to cost $xxx and take ___ this long.
You say Yes or No

OR - the same above, but since you have told them you have a warranty with WD (or whoever), they call WD and they say Yes or No - you already know that you have a $0 or $50 or $xx deductable, so there is no extra effort ... unless they say NO ... and then the SA has to call you.

Give me a break ... this is soooooooooo easy.