Anecdata: I deleted my FB account a few months ago, every few weeks I get an SMS asking if I need help signing in. Also get the same message emailed to original account email address and (!) my work email address - which I've never entered into Facebook.
The work address part is just terrible and totally unethical. Facebook might have gotten your work address from other people who have shared their device/services address books with it, but I thought this is used only for more profiling and targeting, not blatant misuse!
