I also got a 72 hour suspension on one of my accounts last night (1 account out of 10).

My story is the same as yours. No e-mail or notice from Blizzard, had to do a ticket to find out why. They just sent me a canned response. I called Blizzard and they said the same thing - they can't do anything. The ban/locked/suspensions is a separate department and you can't contact them via phone. Only the in-game ticket system is the only recourse.