I 100% agree with everything that's been said in this thread.
Between all three dealers, it took a month and a half to get my car stereo replaced under warranty (ended up having to use Paretti, where I got the aforementioned runaround).
That said, Hollingsworth is probably the lesser of the two Baton Rouge evils. Diamond has had bad attitudes in general for a few years now. At least Hollingsworth puts on a good show of pretending to try to help.
After this car stereo ordeal, I'm never buying another Mazda (and I've sent Mazda NA a letter to that effect).