I'll add my experience...depending upon what side of luck I'd wake up that particular day, I'd get pleasantly surprised (meaning aligned with my expectations of getting the miles), or shocked by seeing the Avis receipt printout the miles, when I returned the rental car.

First few times, I tried following up...toal wastage of my time, not worth it at all...got to a point where I started liking the "surprise" factor, and leave it at that...some things in life (be they miles) are just not worth pursuing, especially with Avis