Did you provide ST your cell phone? Because I was in the same situation (but charges were > $1K), and I usually get a fraud alext text message (not fast, as Citi, in ~5 min) and after that I repeat my transaction.
They do have my cell. And now that you mention it, I usually do get a call or text. Where I'm staying the cell service is very spotty, so maybe that's why I did get the text. I'll try again later when in better cell range. Maybe they wil call then.