Nedbank ***** Department delayed reaction

I effected a transaction for a large amount on my bank account on Friday 7 June at 21h45. Today, on Monday 10 June at 9h45, I received a sms from Nedbank that my card has been placed on hold and that I must contact the ***** Department. Really? What happened to Saturday, which is a banking day? If this was suspected as a ********** transaction, leaving it to Monday wasn't real smart. And a sms? I can still understand the method behind this if you did try to call me and couldn't get hold of me. But placing my card on hold 2,5 days after the transaction took place without a discussion, and then expecting me to phone you to sort it out? Unless my card was actually placed on hold immediately on Friday night, and your sms was just delayed? Very confusing communication made for an unpleasant Monday morning experience...