Switching from Avis
Only after having to fax numerous receipts (which I printed off of Avis.com) to prove they FF# was on the rental have I been able to get any mileage credit to post to DL. I was after the MQM's and none of those have posted. Since it's only 4k, and I won't need them to requalify for Platinum next year --- to heck with it.
I've decided, based on numerous negative experiences with no cars ready, dirty cars, hidden surcharges, not getting FF credit without a fight, etc., it's time to move on to Hertz.