Oh my goodness, I can't believe that! What a horrible thing to have to deal with and on top of it, during a holiday. I wish I knew enough to help! I was speaking with a colleague in my office who handles all of our IT. He said the best way is to wipe all devices and start clean, which you already did. Hopefully the second wipe will prevent any further annoyances.
I think I have a plan.....I'll let you all know how it goes.