These calls might triggered by harassing the reps from "lower your credit card bill" agencies i.e. Rachel from Cardholder Services. I think the reps can put you on a list to be pestered by these robo calls saying you have been removed from their list and they intentionally set them for early morning hours just to piss you off in return. I usually screw with the reps from these companies just to waste their time, but I do it from an office phone that I wont hear at 3am anyway.